From 0c77b3a2307b43d9a2f0c43468766bd5924336f3 Mon Sep 17 00:00:00 2001
From: Martin Felis <martin@fysx.org>
Date: Sat, 24 Oct 2020 11:05:31 +0200
Subject: [PATCH] Transformed srender to a single header library, added
 srcmdbuf_add(cmd);

---
 src/srender.c | 578 +----------------------------------------------
 src/srender.h | 606 +++++++++++++++++++++++++++++++++++++++++++++++++-
 src/vissim.cc |  16 +-
 3 files changed, 616 insertions(+), 584 deletions(-)

diff --git a/src/srender.c b/src/srender.c
index edec532..20ed4ed 100644
--- a/src/srender.c
+++ b/src/srender.c
@@ -2,580 +2,8 @@
 #include <glad/gl.h>
 // clang-format on
 
+#define SRENDER_IMPLEMENTATION
+
 #include "srender.h"
+#undef SRENDER_IMPLEMENTATION
 
-#include "utils.h"
-
-#include <string.h>
-#include <assert.h>
-
-typedef struct srndr {
-} srndr;
-
-typedef struct srview {
-  GLuint width;
-  GLuint height;
-
-  GLuint mFrameBufferId;
-  GLuint mColorTexture;
-  GLuint mDepthTexture;
-
-  simd4x4f proj;
-  simd4x4f view;
-} srview;
-
-typedef struct srcmdbuf {
-  int nbufsize;
-  int ncmds;
-  srcmd* cmds;
-} srcmdbuf;
-
-//
-// Vertex Data
-//
-typedef union srvrtxdata {
-  struct {
-    float x, y, z, w;
-    float nx, ny, nz;
-    float s, t;
-    GLubyte r, g, b, a;
-  };
-  struct {
-    float pos[4];
-    float n[4];
-    float uv[2];
-    GLubyte color[4];
-  };
-} srvrtxdata;
-
-//
-// Vertex Buffer Object for all debug objects (coord frame, grid, cube, ...)
-//
-const GLint DEBUG_VBO_SIZE = 1024;
-GLuint gDebugShapesVBOId = 0;
-GLuint gDebugShapesVAId = 0;
-
-//
-// Simple Mesh Data
-//
-typedef struct srmeshdata {
-  int nvertices;
-  int nindices;
-
-  GLuint vao_id;
-  GLuint vb_id;
-  GLuint idb_id;
-
-  GLuint count;
-  GLenum mode;
-} srmeshdata;
-
-static srmeshdata gCoordFrameMesh = {0};
-static srmeshdata gGridMesh = {0};
-
-typedef struct srshader {
-  const char* vert_fname;
-  const char* frag_fname;
-
-  GLuint program_id;
-  GLuint vert_shader_id;
-  GLuint frag_shader_id;
-} srshader;
-
-static srshader gDefaultShader =
-    {"default_vert.glsl", "default_frag.glsl", 0, 0, 0};
-
-bool srshader_compile(GLuint shader_id, const char* shader_src) {
-  glShaderSource(shader_id, 1, &shader_src, 0);
-  glCompileShader(shader_id);
-
-  // Check Vertex Shader
-  GLint result = GL_FALSE;
-  int log_length = 0;
-  glGetShaderiv(shader_id, GL_COMPILE_STATUS, &result);
-  glGetShaderiv(shader_id, GL_INFO_LOG_LENGTH, &log_length);
-  if (log_length > 0) {
-    char* err_msg = calloc(log_length, sizeof(char));
-    assert(err_msg);
-    glGetShaderInfoLog(shader_id, log_length, NULL, err_msg);
-    gLog("%s", err_msg);
-    free(err_msg);
-
-    return false;
-  }
-
-  return true;
-}
-
-bool srshader_load(
-    srshader* shader,
-    const char* vert_src,
-    const char* frag_src) {
-  shader->vert_shader_id = glCreateShader(GL_VERTEX_SHADER);
-  if (!srshader_compile(shader->vert_shader_id, vert_src)) {
-    gLog("Error compiling vertex shader!");
-    return false;
-  }
-
-  shader->frag_shader_id = glCreateShader(GL_FRAGMENT_SHADER);
-  if (!srshader_compile(shader->frag_shader_id, frag_src)) {
-    gLog("Error compiling fragment shader!");
-    return false;
-  }
-
-  shader->program_id = glCreateProgram();
-  glAttachShader(shader->program_id, shader->vert_shader_id);
-  glAttachShader(shader->program_id, shader->frag_shader_id);
-
-  // Bind attribute locations
-  glBindAttribLocation(shader->program_id, 0, "inCoord");
-  glBindAttribLocation(shader->program_id, 1, "inNormal");
-  glBindAttribLocation(shader->program_id, 2, "inUV");
-  glBindAttribLocation(shader->program_id, 3, "inColor");
-
-  glLinkProgram(shader->program_id);
-
-  GLint result = GL_FALSE;
-  int log_length = 0;
-  glGetProgramiv(shader->program_id, GL_LINK_STATUS, &result);
-  glGetProgramiv(shader->program_id, GL_INFO_LOG_LENGTH, &log_length);
-  if (log_length > 0) {
-    char* err_msg = calloc(log_length, sizeof(char));
-    assert(err_msg);
-    glGetProgramInfoLog(shader->program_id, log_length, NULL, err_msg);
-    gLog("%s", err_msg);
-    free(err_msg);
-    gLog("Error linking shader program!");
-
-    return false;
-  }
-
-  return true;
-}
-
-bool try_read_file(const char* dir, const char* filename, char** buf) {
-  assert(*buf == NULL);
-
-  int path_len = strlen(dir) + strlen(filename) + 1;
-  char* path_buffer = calloc(path_len, sizeof(char));
-  snprintf(path_buffer, path_len, "%s%s", dir, filename);
-  long file_length = 0;
-
-  FILE* file = NULL;
-  file = fopen(path_buffer, "rb");
-  if (file) {
-    fseek(file, 0, SEEK_END);
-    file_length = ftell(file);
-    fseek(file, 0, SEEK_SET);
-    *buf = calloc(file_length, sizeof(char));
-    assert(*buf);
-    fread(*buf, 1, file_length, file);
-    fclose(file);
-
-    return true;
-  }
-
-  return false;
-}
-
-void init_shaders() {
-  static const char* shader_search_paths[] = {
-      "./data/shaders/",
-      "../data/shaders/",
-      NULL};
-
-  bool found = false;
-  int search_index = 0;
-  char* frag_buffer = NULL;
-  char* vert_buffer = NULL;
-
-  while (shader_search_paths[search_index] != NULL) {
-    const char* dir = shader_search_paths[search_index];
-    static char path_buf[1024];
-    long length;
-
-    if (vert_buffer == NULL) {
-      try_read_file(dir, gDefaultShader.vert_fname, &vert_buffer);
-    }
-    if (frag_buffer == NULL) {
-      try_read_file(dir, gDefaultShader.frag_fname, &frag_buffer);
-    }
-
-    if ((vert_buffer != NULL) && (frag_buffer != NULL)) {
-      srshader_load(&gDefaultShader, vert_buffer, frag_buffer);
-
-      free(vert_buffer);
-      vert_buffer = NULL;
-      free(frag_buffer);
-      frag_buffer = NULL;
-      break;
-    }
-
-    search_index++;
-  }
-
-  if (gDefaultShader.program_id == 0) {
-    gLog("Error: could not load default shader!");
-  }
-}
-
-void init_debug_meshes() {
-  assert(gCoordFrameMesh.nvertices == 0);
-
-  glGenVertexArrays(1, &gDebugShapesVAId);
-  glBindVertexArray(gDebugShapesVAId);
-
-  glGenBuffers(1, &gDebugShapesVBOId);
-  glBindBuffer(GL_ARRAY_BUFFER, gDebugShapesVBOId);
-  glBufferData(GL_ARRAY_BUFFER, sizeof(union srvrtxdata) * DEBUG_VBO_SIZE, NULL, GL_STATIC_DRAW);
-
-  GLintptr dbg_vbuf_offset = 0;
-
-  glEnableVertexAttribArray(0);
-  glVertexAttribPointer(
-      0,
-      4,
-      GL_FLOAT,
-      GL_FALSE,
-      (sizeof(srvrtxdata)),
-      (void*)0);
-
-  glEnableVertexAttribArray(1);
-  glVertexAttribPointer(
-      1,
-      3,
-      GL_FLOAT,
-      GL_FALSE,
-      (sizeof(srvrtxdata)),
-      (void*)(sizeof(float) * 4));
-
-  // Attribute 2: texture coordinates
-  glEnableVertexAttribArray(2);
-  glVertexAttribPointer(
-      2,
-      2,
-      GL_FLOAT,
-      GL_FALSE,
-      (sizeof(srvrtxdata)),
-      (void*)(sizeof(float) * 7));
-  // Attribute 3: color
-  glEnableVertexAttribArray(3);
-  glVertexAttribPointer(
-      3,
-      4,
-      GL_UNSIGNED_BYTE,
-      GL_TRUE,
-      (sizeof(srvrtxdata)),
-      (void*)(sizeof(float) * 9));
-
-  //
-  // Coordinate Frame
-  //
-  gCoordFrameMesh.vao_id = gDebugShapesVAId;
-  gCoordFrameMesh.vb_id = gDebugShapesVBOId;
-  gCoordFrameMesh.nvertices = 6;
-
-  srvrtxdata coord_frame_vertices[] = {
-      {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 255, 0, 0, 255},
-      {1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 255, 0, 0, 255},
-
-      {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 255, 0, 255},
-      {0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 255, 0, 255},
-
-      {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 0, 255, 255},
-      {0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 0, 255, 255}};
-  GLuint coord_frame_indices[] = {0, 1, 2, 3, 4, 5};
-
-  glBufferSubData(
-      GL_ARRAY_BUFFER,
-      dbg_vbuf_offset,
-      sizeof(coord_frame_vertices),
-      coord_frame_vertices);
-  dbg_vbuf_offset = sizeof (coord_frame_vertices);
-
-  glGenBuffers(1, &gCoordFrameMesh.idb_id);
-  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gCoordFrameMesh.idb_id);
-  glBufferData(
-      GL_ELEMENT_ARRAY_BUFFER,
-      sizeof(coord_frame_indices),
-      coord_frame_indices,
-      GL_STATIC_DRAW);
-
-  gCoordFrameMesh.mode = GL_LINES;
-  gCoordFrameMesh.count = 6;
-
-  //
-  // Coordinate Frame
-  //
-  gGridMesh.vao_id = gDebugShapesVAId;
-  gGridMesh.vb_id = gDebugShapesVBOId;
-  gGridMesh.nvertices = 44;
-
-  srvrtxdata* grid_vertices = calloc(44, sizeof(srvrtxdata));
-  srvrtxdata grid_def_vertex = {
-      0.f, 0.f, 0.f, 1.f,
-      0.f, 1.f, 0.f,
-      0.f, 0.f,
-      255, 255, 255, 255
-  };
-  // lines along parallel to x axis
-  for (int i = 0; i <= 10; i++) {
-    memcpy (&grid_vertices[2*i], &grid_def_vertex, sizeof(srvrtxdata));
-    memcpy (&grid_vertices[2*i + 1], &grid_def_vertex, sizeof(srvrtxdata));
-    grid_vertices[2 * i].pos[0] = -5.0f + i * 1.0f;
-    grid_vertices[2 * i].pos[2] = 5.0f;
-    grid_vertices[2 * i + 1].pos[0] = -5.0f + i * 1.0f;
-    grid_vertices[2 * i + 1].pos[2] = -5.0f;
-  }
-  // lines parallel to z axis
-  for (int i = 11; i <= 21; i++) {
-    memcpy (&grid_vertices[2*i], &grid_def_vertex, sizeof(srvrtxdata));
-    memcpy (&grid_vertices[2*i + 1], &grid_def_vertex, sizeof(srvrtxdata));
-    grid_vertices[2 * i].pos[0] = -5.0f;
-    grid_vertices[2 * i].pos[2] = -5.0f + (i - 11) * 1.0f;
-    grid_vertices[2 * i + 1].pos[0] = 5.0f;
-    grid_vertices[2 * i + 1].pos[2] = -5.0f + (i - 11) * 1.0f;
-  }
-
-  glBindBuffer(GL_ARRAY_BUFFER, gDebugShapesVBOId);
-  glBufferSubData(
-      GL_ARRAY_BUFFER,
-      dbg_vbuf_offset,
-      sizeof(srvrtxdata) * 44,
-      grid_vertices);
-  dbg_vbuf_offset += sizeof (srvrtxdata) * 44;
-
-  free(grid_vertices);
-
-  GLuint grid_indices[44];
-  for (int i = 0; i < 22; i++) {
-    grid_indices[2 * i] = 2*i + 6;
-    grid_indices[2 * i + 1] = (2*i+1) + 6;
-  }
-
-  glGenBuffers(1, &gGridMesh.idb_id);
-  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gGridMesh.idb_id);
-  glBufferData(
-      GL_ELEMENT_ARRAY_BUFFER,
-      sizeof(grid_indices),
-      grid_indices,
-      GL_STATIC_DRAW);
-
-  gGridMesh.mode = GL_LINES;
-  gGridMesh.count = 44;
-
-  glBindVertexArray(0);
-};
-
-//
-// Renderer
-//
-srndr* srndr_create() {
-  srndr* result = calloc(1, sizeof(srndr));
-
-  init_shaders();
-  init_debug_meshes();
-
-  return result;
-}
-
-void srndr_destroy(srndr* sr) { free(sr); }
-
-//
-// View
-//
-void srview_get_output_texture(srview* sv, GLuint* texture) {
-  *texture = sv->mColorTexture;
-}
-
-void srview_set_proj(srview* sv, simd4x4f proj) { sv->proj = proj; }
-
-void srview_set_view(srview* sv, simd4x4f view) { sv->view = view; }
-
-void srview_update_framebuffer(srview* sv) {
-  glGenFramebuffers(1, &sv->mFrameBufferId);
-  glBindFramebuffer(GL_FRAMEBUFFER, sv->mFrameBufferId);
-
-  // Color Texture
-  glGenTextures(1, &sv->mColorTexture);
-  glBindTexture(GL_TEXTURE_2D, sv->mColorTexture);
-
-  glTexImage2D(
-      GL_TEXTURE_2D,
-      0,
-      GL_RGB,
-      sv->width,
-      sv->height,
-      0,
-      GL_RGB,
-      GL_UNSIGNED_BYTE,
-      0);
-
-  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
-  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-
-  glFramebufferTexture2D(
-      GL_FRAMEBUFFER,
-      GL_COLOR_ATTACHMENT0,
-      GL_TEXTURE_2D,
-      sv->mColorTexture,
-      0);
-
-  // Depth Texture
-  glGenTextures(1, &sv->mDepthTexture);
-  glBindTexture(GL_TEXTURE_2D, sv->mDepthTexture);
-
-  glTexImage2D(
-      GL_TEXTURE_2D,
-      0,
-      GL_DEPTH_COMPONENT,
-      sv->width,
-      sv->height,
-      0,
-      GL_DEPTH_COMPONENT,
-      GL_FLOAT,
-      0);
-
-  // Set parameters so that we can set a shadow2DSampler
-  glTexParameteri(
-      GL_TEXTURE_2D,
-      GL_TEXTURE_COMPARE_MODE,
-      GL_COMPARE_REF_TO_TEXTURE);
-  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
-  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
-  float border_color[] = {1.0f, 1.0f, 1.0f, 1.0f};
-  glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, border_color);
-
-  glFramebufferTexture2D(
-      GL_FRAMEBUFFER,
-      GL_DEPTH_ATTACHMENT,
-      GL_TEXTURE_2D,
-      sv->mDepthTexture,
-      0);
-}
-
-void srview_cleanup_framebuffer(srview* sv) {
-  if (glIsFramebuffer(sv->mFrameBufferId)) {
-    glDeleteFramebuffers(1, &sv->mFrameBufferId);
-  }
-
-  if (sv->mColorTexture != -1) {
-    glDeleteTextures(1, &sv->mColorTexture);
-    sv->mColorTexture = -1;
-  }
-
-  if (sv->mDepthTexture != -1) {
-    glDeleteTextures(1, &sv->mDepthTexture);
-    sv->mDepthTexture = -1;
-  }
-}
-
-void srview_set_size(srview* sv, int width, int height) {
-  if (sv->width == width && sv->height == height) {
-    return;
-  }
-
-  sv->width = width;
-  sv->height = height;
-
-  srview_cleanup_framebuffer(sv);
-  srview_update_framebuffer(sv);
-}
-
-srview* srview_create() {
-  srview* result = calloc(1, sizeof(srview));
-
-  return result;
-}
-
-void srview_destroy(srview* sv) {
-  srview_cleanup_framebuffer(sv);
-
-  free(sv);
-}
-
-void srndr_run_frame_command(const srcmd* cmd) {
-  glBindVertexArray(gCoordFrameMesh.vao_id);
-
-  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gCoordFrameMesh.idb_id);
-  glDrawElements(gCoordFrameMesh.mode, gCoordFrameMesh.count, GL_UNSIGNED_INT, (void*)0);
-
-  glBindBuffer(GL_ARRAY_BUFFER, 0);
-  glBindVertexArray(0);
-}
-
-void srndr_run_grid_command(const srcmd* cmd) {
-  glBindVertexArray(gGridMesh.vao_id);
-
-  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gGridMesh.idb_id);
-  glDrawElements(gGridMesh.mode, gGridMesh.count, GL_UNSIGNED_INT, (void*)0);
-
-  glBindBuffer(GL_ARRAY_BUFFER, 0);
-  glBindVertexArray(0);
-}
-
-void srndr_render(srndr* srndr, srview* sview, srcmdbuf* scmdbuf) {
-  glBindFramebuffer(GL_DRAW_FRAMEBUFFER, sview->mFrameBufferId);
-
-  glViewport(0, 0, sview->width, sview->height);
-  glClearColor(0.1f, 0.1f, 0.1f, 0.1f);
-  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-
-  glUseProgram(gDefaultShader.program_id);
-  GLint view_mat_loc =
-      glGetUniformLocation(gDefaultShader.program_id, "uViewMatrix");
-  assert(view_mat_loc != -1);
-  glUniformMatrix4fv(view_mat_loc, 1, GL_FALSE, &sview->view);
-
-  GLint proj_mat_loc =
-      glGetUniformLocation(gDefaultShader.program_id, "uProjectionMatrix");
-  assert(proj_mat_loc != -1);
-  glUniformMatrix4fv(proj_mat_loc, 1, GL_FALSE, &sview->proj);
-
-  GLint model_mat_loc =
-      glGetUniformLocation(gDefaultShader.program_id, "uModelMatrix");
-  assert(model_mat_loc != -1);
-
-  for (int i = 0; i < scmdbuf->ncmds; i++) {
-    const srcmd* cmd = &scmdbuf->cmds[i];
-    glUniformMatrix4fv(model_mat_loc, 1, GL_FALSE, &cmd->mat);
-
-    switch (cmd->type) {
-      case SRndrCmdTypeFrame:
-        srndr_run_frame_command(cmd);
-        break;
-      case SRndrCmdTypeGrid:
-        srndr_run_grid_command(cmd);
-        break;
-      default:
-        gLog("Invalid command type %d at index %d", cmd->type, i);
-        break;
-    }
-  }
-
-  glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
-}
-
-//
-// Render Commands
-//
-srcmdbuf* srcmdbuf_create(unsigned int size_max) {
-  srcmdbuf* result = malloc(sizeof(srcmdbuf));
-  result->nbufsize = size_max;
-  result->ncmds = 0;
-  result->cmds = calloc(sizeof(srcmd), size_max);
-
-  return result;
-}
-
-void srcmdbuf_clear(srcmdbuf* cmdbuf) { cmdbuf->ncmds = 0; }
-
-srcmd* srcmd_create(srcmdbuf* cmdbuf) {
-  if (cmdbuf->ncmds == cmdbuf->nbufsize) {
-    gLog("Warning: number of render commands maxed out!");
-    return NULL;
-  }
-  return &(cmdbuf->cmds[cmdbuf->ncmds++]);
-}
diff --git a/src/srender.h b/src/srender.h
index a4277b0..9947afc 100644
--- a/src/srender.h
+++ b/src/srender.h
@@ -5,6 +5,7 @@
 extern "C" {
 #endif
 
+#include <stdbool.h>
 #include "vectorial/simd4x4f.h"
 
 typedef struct srndr srndr;
@@ -45,14 +46,617 @@ void srview_get_output_texture(srview* sv, GLuint* texture);
 //
 // Command Buffer and Commands
 //
+void srcmd_clear (srcmd *cmd);
+
 srcmdbuf* srcmdbuf_create(unsigned int size_max);
 void srcmdbuf_clear(srcmdbuf* cmdbuf);
+bool srcmdbuf_add(srcmdbuf* cmdbuf, srcmd *cmd);
 srcmd* srcmd_create(srcmdbuf* cmdbuf);
 
 void srndr_render(srndr* srndr, srview* sview, srcmdbuf* scmdbuf);
 
+//
+// srender Implementation
+//
+
+#ifdef SRENDER_IMPLEMENTATION
+
+#include "utils.h"
+
+#include <string.h>
+#include <assert.h>
+
+typedef struct srndr {
+} srndr;
+
+typedef struct srview {
+  GLuint width;
+  GLuint height;
+
+  GLuint mFrameBufferId;
+  GLuint mColorTexture;
+  GLuint mDepthTexture;
+
+  simd4x4f proj;
+  simd4x4f view;
+} srview;
+
+typedef struct srcmdbuf {
+  int nbufsize;
+  int ncmds;
+  srcmd* cmds;
+} srcmdbuf;
+
+//
+// Vertex Data
+//
+typedef union srvrtxdata {
+  struct {
+    float x, y, z, w;
+    float nx, ny, nz;
+    float s, t;
+    GLubyte r, g, b, a;
+  };
+  struct {
+    float pos[4];
+    float n[4];
+    float uv[2];
+    GLubyte color[4];
+  };
+} srvrtxdata;
+
+//
+// Vertex Buffer Object for all debug objects (coord frame, grid, cube, ...)
+//
+const GLint DEBUG_VBO_SIZE = 1024;
+GLuint gDebugShapesVBOId = 0;
+GLuint gDebugShapesVAId = 0;
+
+//
+// Simple Mesh Data
+//
+typedef struct srmeshdata {
+  int nvertices;
+  int nindices;
+
+  GLuint vao_id;
+  GLuint vb_id;
+  GLuint idb_id;
+
+  GLuint count;
+  GLenum mode;
+} srmeshdata;
+
+static srmeshdata gCoordFrameMesh = {0};
+static srmeshdata gGridMesh = {0};
+
+typedef struct srshader {
+  const char* vert_fname;
+  const char* frag_fname;
+
+  GLuint program_id;
+  GLuint vert_shader_id;
+  GLuint frag_shader_id;
+} srshader;
+
+static srshader gDefaultShader =
+    {"default_vert.glsl", "default_frag.glsl", 0, 0, 0};
+
+bool srshader_compile(GLuint shader_id, const char* shader_src) {
+  glShaderSource(shader_id, 1, &shader_src, 0);
+  glCompileShader(shader_id);
+
+  // Check Vertex Shader
+  GLint result = GL_FALSE;
+  int log_length = 0;
+  glGetShaderiv(shader_id, GL_COMPILE_STATUS, &result);
+  glGetShaderiv(shader_id, GL_INFO_LOG_LENGTH, &log_length);
+  if (log_length > 0) {
+    char* err_msg = calloc(log_length, sizeof(char));
+    assert(err_msg);
+    glGetShaderInfoLog(shader_id, log_length, NULL, err_msg);
+    gLog("%s", err_msg);
+    free(err_msg);
+
+    return false;
+  }
+
+  return true;
+}
+
+bool srshader_load(
+    srshader* shader,
+    const char* vert_src,
+    const char* frag_src) {
+  shader->vert_shader_id = glCreateShader(GL_VERTEX_SHADER);
+  if (!srshader_compile(shader->vert_shader_id, vert_src)) {
+    gLog("Error compiling vertex shader!");
+    return false;
+  }
+
+  shader->frag_shader_id = glCreateShader(GL_FRAGMENT_SHADER);
+  if (!srshader_compile(shader->frag_shader_id, frag_src)) {
+    gLog("Error compiling fragment shader!");
+    return false;
+  }
+
+  shader->program_id = glCreateProgram();
+  glAttachShader(shader->program_id, shader->vert_shader_id);
+  glAttachShader(shader->program_id, shader->frag_shader_id);
+
+  // Bind attribute locations
+  glBindAttribLocation(shader->program_id, 0, "inCoord");
+  glBindAttribLocation(shader->program_id, 1, "inNormal");
+  glBindAttribLocation(shader->program_id, 2, "inUV");
+  glBindAttribLocation(shader->program_id, 3, "inColor");
+
+  glLinkProgram(shader->program_id);
+
+  GLint result = GL_FALSE;
+  int log_length = 0;
+  glGetProgramiv(shader->program_id, GL_LINK_STATUS, &result);
+  glGetProgramiv(shader->program_id, GL_INFO_LOG_LENGTH, &log_length);
+  if (log_length > 0) {
+    char* err_msg = calloc(log_length, sizeof(char));
+    assert(err_msg);
+    glGetProgramInfoLog(shader->program_id, log_length, NULL, err_msg);
+    gLog("%s", err_msg);
+    free(err_msg);
+    gLog("Error linking shader program!");
+
+    return false;
+  }
+
+  return true;
+}
+
+bool try_read_file(const char* dir, const char* filename, char** buf) {
+  assert(*buf == NULL);
+
+  int path_len = strlen(dir) + strlen(filename) + 1;
+  char* path_buffer = calloc(path_len, sizeof(char));
+  snprintf(path_buffer, path_len, "%s%s", dir, filename);
+  long file_length = 0;
+
+  FILE* file = NULL;
+  file = fopen(path_buffer, "rb");
+  if (file) {
+    fseek(file, 0, SEEK_END);
+    file_length = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    *buf = calloc(file_length, sizeof(char));
+    assert(*buf);
+    fread(*buf, 1, file_length, file);
+    fclose(file);
+
+    return true;
+  }
+
+  return false;
+}
+
+void init_shaders() {
+  static const char* shader_search_paths[] = {
+      "./data/shaders/",
+      "../data/shaders/",
+      NULL};
+
+  bool found = false;
+  int search_index = 0;
+  char* frag_buffer = NULL;
+  char* vert_buffer = NULL;
+
+  while (shader_search_paths[search_index] != NULL) {
+    const char* dir = shader_search_paths[search_index];
+    static char path_buf[1024];
+    long length;
+
+    if (vert_buffer == NULL) {
+      try_read_file(dir, gDefaultShader.vert_fname, &vert_buffer);
+    }
+    if (frag_buffer == NULL) {
+      try_read_file(dir, gDefaultShader.frag_fname, &frag_buffer);
+    }
+
+    if ((vert_buffer != NULL) && (frag_buffer != NULL)) {
+      srshader_load(&gDefaultShader, vert_buffer, frag_buffer);
+
+      free(vert_buffer);
+      vert_buffer = NULL;
+      free(frag_buffer);
+      frag_buffer = NULL;
+      break;
+    }
+
+    search_index++;
+  }
+
+  if (gDefaultShader.program_id == 0) {
+    gLog("Error: could not load default shader!");
+  }
+}
+
+void init_debug_meshes() {
+  assert(gCoordFrameMesh.nvertices == 0);
+
+  glGenVertexArrays(1, &gDebugShapesVAId);
+  glBindVertexArray(gDebugShapesVAId);
+
+  glGenBuffers(1, &gDebugShapesVBOId);
+  glBindBuffer(GL_ARRAY_BUFFER, gDebugShapesVBOId);
+  glBufferData(GL_ARRAY_BUFFER, sizeof(union srvrtxdata) * DEBUG_VBO_SIZE, NULL, GL_STATIC_DRAW);
+
+  GLintptr dbg_vbuf_offset = 0;
+
+  glEnableVertexAttribArray(0);
+  glVertexAttribPointer(
+      0,
+      4,
+      GL_FLOAT,
+      GL_FALSE,
+      (sizeof(srvrtxdata)),
+      (void*)0);
+
+  glEnableVertexAttribArray(1);
+  glVertexAttribPointer(
+      1,
+      3,
+      GL_FLOAT,
+      GL_FALSE,
+      (sizeof(srvrtxdata)),
+      (void*)(sizeof(float) * 4));
+
+  // Attribute 2: texture coordinates
+  glEnableVertexAttribArray(2);
+  glVertexAttribPointer(
+      2,
+      2,
+      GL_FLOAT,
+      GL_FALSE,
+      (sizeof(srvrtxdata)),
+      (void*)(sizeof(float) * 7));
+  // Attribute 3: color
+  glEnableVertexAttribArray(3);
+  glVertexAttribPointer(
+      3,
+      4,
+      GL_UNSIGNED_BYTE,
+      GL_TRUE,
+      (sizeof(srvrtxdata)),
+      (void*)(sizeof(float) * 9));
+
+  //
+  // Coordinate Frame
+  //
+  gCoordFrameMesh.vao_id = gDebugShapesVAId;
+  gCoordFrameMesh.vb_id = gDebugShapesVBOId;
+  gCoordFrameMesh.nvertices = 6;
+
+  srvrtxdata coord_frame_vertices[] = {
+      {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 255, 0, 0, 255},
+      {1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 255, 0, 0, 255},
+
+      {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 255, 0, 255},
+      {0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 255, 0, 255},
+
+      {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 0, 255, 255},
+      {0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0, 0, 255, 255}};
+  GLuint coord_frame_indices[] = {0, 1, 2, 3, 4, 5};
+
+  glBufferSubData(
+      GL_ARRAY_BUFFER,
+      dbg_vbuf_offset,
+      sizeof(coord_frame_vertices),
+      coord_frame_vertices);
+  dbg_vbuf_offset = sizeof (coord_frame_vertices);
+
+  glGenBuffers(1, &gCoordFrameMesh.idb_id);
+  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gCoordFrameMesh.idb_id);
+  glBufferData(
+      GL_ELEMENT_ARRAY_BUFFER,
+      sizeof(coord_frame_indices),
+      coord_frame_indices,
+      GL_STATIC_DRAW);
+
+  gCoordFrameMesh.mode = GL_LINES;
+  gCoordFrameMesh.count = 6;
+
+  //
+  // Coordinate Frame
+  //
+  gGridMesh.vao_id = gDebugShapesVAId;
+  gGridMesh.vb_id = gDebugShapesVBOId;
+  gGridMesh.nvertices = 44;
+
+  srvrtxdata* grid_vertices = calloc(44, sizeof(srvrtxdata));
+  srvrtxdata grid_def_vertex = {
+      0.f, 0.f, 0.f, 1.f,
+      0.f, 1.f, 0.f,
+      0.f, 0.f,
+      255, 255, 255, 255
+  };
+  // lines along parallel to x axis
+  for (int i = 0; i <= 10; i++) {
+    memcpy (&grid_vertices[2*i], &grid_def_vertex, sizeof(srvrtxdata));
+    memcpy (&grid_vertices[2*i + 1], &grid_def_vertex, sizeof(srvrtxdata));
+    grid_vertices[2 * i].pos[0] = -5.0f + i * 1.0f;
+    grid_vertices[2 * i].pos[2] = 5.0f;
+    grid_vertices[2 * i + 1].pos[0] = -5.0f + i * 1.0f;
+    grid_vertices[2 * i + 1].pos[2] = -5.0f;
+  }
+  // lines parallel to z axis
+  for (int i = 11; i <= 21; i++) {
+    memcpy (&grid_vertices[2*i], &grid_def_vertex, sizeof(srvrtxdata));
+    memcpy (&grid_vertices[2*i + 1], &grid_def_vertex, sizeof(srvrtxdata));
+    grid_vertices[2 * i].pos[0] = -5.0f;
+    grid_vertices[2 * i].pos[2] = -5.0f + (i - 11) * 1.0f;
+    grid_vertices[2 * i + 1].pos[0] = 5.0f;
+    grid_vertices[2 * i + 1].pos[2] = -5.0f + (i - 11) * 1.0f;
+  }
+
+  glBindBuffer(GL_ARRAY_BUFFER, gDebugShapesVBOId);
+  glBufferSubData(
+      GL_ARRAY_BUFFER,
+      dbg_vbuf_offset,
+      sizeof(srvrtxdata) * 44,
+      grid_vertices);
+  dbg_vbuf_offset += sizeof (srvrtxdata) * 44;
+
+  free(grid_vertices);
+
+  GLuint grid_indices[44];
+  for (int i = 0; i < 22; i++) {
+    grid_indices[2 * i] = 2*i + 6;
+    grid_indices[2 * i + 1] = (2*i+1) + 6;
+  }
+
+  glGenBuffers(1, &gGridMesh.idb_id);
+  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gGridMesh.idb_id);
+  glBufferData(
+      GL_ELEMENT_ARRAY_BUFFER,
+      sizeof(grid_indices),
+      grid_indices,
+      GL_STATIC_DRAW);
+
+  gGridMesh.mode = GL_LINES;
+  gGridMesh.count = 44;
+
+  glBindVertexArray(0);
+};
+
+//
+// Renderer
+//
+srndr* srndr_create() {
+  srndr* result = calloc(1, sizeof(srndr));
+
+  init_shaders();
+  init_debug_meshes();
+
+  return result;
+}
+
+void srndr_destroy(srndr* sr) { free(sr); }
+
+//
+// View
+//
+void srview_get_output_texture(srview* sv, GLuint* texture) {
+  *texture = sv->mColorTexture;
+}
+
+void srview_set_proj(srview* sv, simd4x4f proj) { sv->proj = proj; }
+
+void srview_set_view(srview* sv, simd4x4f view) { sv->view = view; }
+
+void srview_update_framebuffer(srview* sv) {
+  glGenFramebuffers(1, &sv->mFrameBufferId);
+  glBindFramebuffer(GL_FRAMEBUFFER, sv->mFrameBufferId);
+
+  // Color Texture
+  glGenTextures(1, &sv->mColorTexture);
+  glBindTexture(GL_TEXTURE_2D, sv->mColorTexture);
+
+  glTexImage2D(
+      GL_TEXTURE_2D,
+      0,
+      GL_RGB,
+      sv->width,
+      sv->height,
+      0,
+      GL_RGB,
+      GL_UNSIGNED_BYTE,
+      0);
+
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+
+  glFramebufferTexture2D(
+      GL_FRAMEBUFFER,
+      GL_COLOR_ATTACHMENT0,
+      GL_TEXTURE_2D,
+      sv->mColorTexture,
+      0);
+
+  // Depth Texture
+  glGenTextures(1, &sv->mDepthTexture);
+  glBindTexture(GL_TEXTURE_2D, sv->mDepthTexture);
+
+  glTexImage2D(
+      GL_TEXTURE_2D,
+      0,
+      GL_DEPTH_COMPONENT,
+      sv->width,
+      sv->height,
+      0,
+      GL_DEPTH_COMPONENT,
+      GL_FLOAT,
+      0);
+
+  // Set parameters so that we can set a shadow2DSampler
+  glTexParameteri(
+      GL_TEXTURE_2D,
+      GL_TEXTURE_COMPARE_MODE,
+      GL_COMPARE_REF_TO_TEXTURE);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
+  float border_color[] = {1.0f, 1.0f, 1.0f, 1.0f};
+  glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, border_color);
+
+  glFramebufferTexture2D(
+      GL_FRAMEBUFFER,
+      GL_DEPTH_ATTACHMENT,
+      GL_TEXTURE_2D,
+      sv->mDepthTexture,
+      0);
+}
+
+void srview_cleanup_framebuffer(srview* sv) {
+  if (glIsFramebuffer(sv->mFrameBufferId)) {
+    glDeleteFramebuffers(1, &sv->mFrameBufferId);
+  }
+
+  if (sv->mColorTexture != -1) {
+    glDeleteTextures(1, &sv->mColorTexture);
+    sv->mColorTexture = -1;
+  }
+
+  if (sv->mDepthTexture != -1) {
+    glDeleteTextures(1, &sv->mDepthTexture);
+    sv->mDepthTexture = -1;
+  }
+}
+
+void srview_set_size(srview* sv, int width, int height) {
+  if (sv->width == width && sv->height == height) {
+    return;
+  }
+
+  sv->width = width;
+  sv->height = height;
+
+  srview_cleanup_framebuffer(sv);
+  srview_update_framebuffer(sv);
+}
+
+srview* srview_create() {
+  srview* result = calloc(1, sizeof(srview));
+
+  return result;
+}
+
+void srview_destroy(srview* sv) {
+  srview_cleanup_framebuffer(sv);
+
+  free(sv);
+}
+
+void srndr_run_frame_command(const srcmd* cmd) {
+  glBindVertexArray(gCoordFrameMesh.vao_id);
+
+  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gCoordFrameMesh.idb_id);
+  glDrawElements(gCoordFrameMesh.mode, gCoordFrameMesh.count, GL_UNSIGNED_INT, (void*)0);
+
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+  glBindVertexArray(0);
+}
+
+void srndr_run_grid_command(const srcmd* cmd) {
+  glBindVertexArray(gGridMesh.vao_id);
+
+  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gGridMesh.idb_id);
+  glDrawElements(gGridMesh.mode, gGridMesh.count, GL_UNSIGNED_INT, (void*)0);
+
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+  glBindVertexArray(0);
+}
+
+void srndr_render(srndr* srndr, srview* sview, srcmdbuf* scmdbuf) {
+  glBindFramebuffer(GL_DRAW_FRAMEBUFFER, sview->mFrameBufferId);
+
+  glViewport(0, 0, sview->width, sview->height);
+  glClearColor(0.1f, 0.1f, 0.1f, 0.1f);
+  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+  glUseProgram(gDefaultShader.program_id);
+  GLint view_mat_loc =
+      glGetUniformLocation(gDefaultShader.program_id, "uViewMatrix");
+  assert(view_mat_loc != -1);
+  glUniformMatrix4fv(view_mat_loc, 1, GL_FALSE, &sview->view);
+
+  GLint proj_mat_loc =
+      glGetUniformLocation(gDefaultShader.program_id, "uProjectionMatrix");
+  assert(proj_mat_loc != -1);
+  glUniformMatrix4fv(proj_mat_loc, 1, GL_FALSE, &sview->proj);
+
+  GLint model_mat_loc =
+      glGetUniformLocation(gDefaultShader.program_id, "uModelMatrix");
+  assert(model_mat_loc != -1);
+
+  for (int i = 0; i < scmdbuf->ncmds; i++) {
+    const srcmd* cmd = &scmdbuf->cmds[i];
+    glUniformMatrix4fv(model_mat_loc, 1, GL_FALSE, &cmd->mat);
+
+    switch (cmd->type) {
+      case SRndrCmdTypeFrame:
+        srndr_run_frame_command(cmd);
+        break;
+      case SRndrCmdTypeGrid:
+        srndr_run_grid_command(cmd);
+        break;
+      default:
+        gLog("Invalid command type %d at index %d", cmd->type, i);
+        break;
+    }
+  }
+
+  glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
+}
+
+//
+// Render Commands
+//
+void srcmd_clear (srcmd *cmd) {
+  cmd->color = simd4f_create(1.f, 1.f, 1.f, 1.f);
+  cmd->type = SRndrCmdTypeFrame;
+  simd4x4f_identity(&cmd->mat);
+}
+
+srcmdbuf* srcmdbuf_create(unsigned int size_max) {
+  srcmdbuf* result = malloc(sizeof(srcmdbuf));
+  result->nbufsize = size_max;
+  result->ncmds = 0;
+  result->cmds = calloc(sizeof(srcmd), size_max);
+
+  return result;
+}
+
+void srcmdbuf_clear(srcmdbuf* cmdbuf) { cmdbuf->ncmds = 0; }
+
+bool srcmdbuf_add(srcmdbuf* cmdbuf, srcmd *cmd) {
+  srcmd *buf_cmd = srcmd_create(cmdbuf);
+
+  if (!buf_cmd) {
+    return false;
+  }
+
+  *buf_cmd = *cmd;
+}
+
+srcmd* srcmd_create(srcmdbuf* cmdbuf) {
+  if (cmdbuf->ncmds == cmdbuf->nbufsize) {
+    gLog("Warning: number of render commands maxed out!");
+    return NULL;
+  }
+  return &(cmdbuf->cmds[cmdbuf->ncmds++]);
+}
+
+#endif // SRENDER_IMPLEMENTATION
+
 #ifdef __cplusplus
 }
 #endif
 
-#endif
+#endif // SRENDER_H
diff --git a/src/vissim.cc b/src/vissim.cc
index aa52844..1ed3e20 100644
--- a/src/vissim.cc
+++ b/src/vissim.cc
@@ -187,15 +187,15 @@ void DoRender() {
 
   // Populate render commands
   srcmdbuf_clear(gRndrCmds);
-  srcmd* cmd = srcmd_create(gRndrCmds);
-  cmd->type = SRndrCmdTypeFrame;
-  simd4x4f_identity(&cmd->mat);
-  cmd->color = simd4f_create(1.f, 1.f, 1.f, 1.f);
 
-  cmd = srcmd_create(gRndrCmds);
-  cmd->type = SRndrCmdTypeGrid;
-  simd4x4f_identity(&cmd->mat);
-  cmd->color = simd4f_create(1.f, 1.f, 1.f, 1.f);
+  srcmd rcmd;
+  srcmd_clear(&rcmd);
+
+  rcmd.type = SRndrCmdTypeFrame;
+  srcmdbuf_add(gRndrCmds, &rcmd);
+
+  rcmd.type = SRndrCmdTypeGrid;
+  srcmdbuf_add(gRndrCmds, &rcmd);
 
   // Perform the actual render
   srndr_render(gRndr, gView, gRndrCmds);