wip framebuffers

shaders/frag.glsl

@@ -2,8 +2,10 @@
 
 uniform float iTime;
 uniform vec2 iResolution;
+uniform sampler2D frame0;
 in vec2 vUV;
 out vec4 fragColor;
+layout(location = 0) out vec4 fragColor2;
 
 void main() {
     vec2 uv0 = vUV.st;
@@ -12,4 +14,5 @@ void main() {
     vec3 color = vec3(vUV, sin(iTime * 0.5) * 0.5 + 0.5);
     color *= 1 - step(cos(iTime) * 0.1 + 0.5,length(uv1));
     fragColor = vec4(color, 1.0);
+    fragColor2 = vec4(color, 1.0);
 }

src/config.h

@@ -9,4 +9,12 @@
 #define VERSION "(dev)"
 #endif
 
+#ifndef FRAMEBUFFER_IDS
+#define FRAMEBUFFER_IDS {0, 1, 2, 3, 4, 5, 6, 7}
+#endif
+
+#ifndef BUFFER_COUNT
+#define BUFFER_COUNT 8
+#endif
+
 #endif

src/forge.c

@@ -59,6 +59,7 @@ void forge_run(Parameters params) {
   ShaderProgram program;
   Window *window;
   Timer timer;
+  Context context;
 
   fragment_shader = read_file(params.frag_path);
 
@@ -69,7 +70,9 @@ void forge_run(Parameters params) {
   window = init_window(PACKAGE " " VERSION, params.screen, error_callback,
                        key_callback);
 
-  program = init_program(fragment_shader);
+  context = get_window_context(window);
+
+  program = init_program(fragment_shader, context);
 
   if (program.error) {
     close_window(window, true);

src/shaders.c

@@ -2,6 +2,7 @@
 #include <linmath.h>
 #include <stddef.h>
 
+#include "config.h"
 #include "constants.h"
 #include "logs.h"
 #include "types.h"
@@ -31,14 +32,67 @@ bool compile_shader(GLuint shader_id, char *name, char *source_code) {
   return status_params == GL_TRUE;
 }
 
-ShaderProgram init_program(File fragment_shader) {
-  ShaderProgram program = {0};
+ShaderProgram init_program(File fragment_shader, Context context) {
+  int i, j;
+  GLenum draw_buffers[BUFFER_COUNT];
+  char uniform_name[32];
+
+  for (i = 0; i < BUFFER_COUNT; i++) {
+    draw_buffers[i] = GL_COLOR_ATTACHMENT0 + i;
+  }
+
+  ShaderProgram program = {.error = false, .frame_buffers = FRAMEBUFFER_IDS};
 
   // create vertex buffer and setup vertices
   glGenBuffers(1, &program.vertex_buffer);
   glBindBuffer(GL_ARRAY_BUFFER, program.vertex_buffer);
   glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 
+  // create framebuffers and textures
+  glGenTextures(1, program.textures);
+  glGenFramebuffers(BUFFER_COUNT, program.frame_buffers);
+  glGenRenderbuffers(BUFFER_COUNT, program.render_buffers);
+  for (i = 0; i < BUFFER_COUNT; i++) {
+    glTextureParameteri(program.textures[i], GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTextureParameteri(program.textures[i], GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTextureParameteri(program.textures[i], GL_TEXTURE_WRAP_S,
+                        GL_CLAMP_TO_EDGE);
+    glTextureParameteri(program.textures[i], GL_TEXTURE_WRAP_T,
+                        GL_CLAMP_TO_EDGE);
+
+    glBindTexture(GL_TEXTURE_2D, program.textures[i]);
+
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, context.width, context.height, 0,
+                 GL_RGB, GL_UNSIGNED_BYTE, 0);
+
+    glBindRenderbuffer(GL_RENDERBUFFER, program.render_buffers[i]);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, context.width,
+                          context.height);
+    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
+                              GL_RENDERBUFFER, program.render_buffers[i]);
+
+    glBindFramebuffer(GL_FRAMEBUFFER, program.frame_buffers[i]);
+
+    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
+                              GL_RENDERBUFFER, program.render_buffers[i]);
+
+    for (j = 0; j < BUFFER_COUNT; j++) {
+      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + j,
+                             GL_TEXTURE_2D, program.textures[j], 0);
+    }
+
+    glDrawBuffers(BUFFER_COUNT, draw_buffers);
+
+    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
+      log_error("Framebuffer %d is KO: %x", i,
+                glCheckFramebufferStatus(GL_FRAMEBUFFER));
+      program.error = true;
+      return program;
+    }
+  }
+
+  glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
   // compile vertex shader
   program.vertex_shader = glCreateShader(GL_VERTEX_SHADER);
   program.error |= !compile_shader(
@@ -64,6 +118,12 @@ ShaderProgram init_program(File fragment_shader) {
   program.itime_location = glGetUniformLocation(program.program, "iTime");
   program.ires_location = glGetUniformLocation(program.program, "iResolution");
 
+  for (i = 0; i < BUFFER_COUNT; i++) {
+    sprintf(uniform_name, "frame%d", i);
+    program.frames_location[i] =
+        glGetUniformLocation(program.program, uniform_name);
+  }
+
   // create attribute pointer
   program.vpos_location = glGetAttribLocation(program.program, "vPos");
 

src/shaders.h

@@ -3,7 +3,7 @@
 #ifndef SHADERS_H
 #define SHADERS_H
 
-ShaderProgram init_program(File fragment_shader);
+ShaderProgram init_program(File fragment_shader, Context context);
 
 void update_program(ShaderProgram program, File fragment_shader);
 

src/types.h

@@ -5,6 +5,8 @@
 #include <sys/time.h>
 #include <time.h>
 
+#include "config.h"
+
 #ifndef TYPES_H
 #define TYPES_H
 
@@ -36,10 +38,15 @@ typedef struct ShaderProgram {
   GLuint mvp_location;
   GLuint itime_location;
   GLuint ires_location;
+  GLuint frames_location[BUFFER_COUNT];
 
   GLuint vertex_buffer;
   GLuint vertex_array;
   GLuint vpos_location;
+
+  GLuint frame_buffers[BUFFER_COUNT];
+  GLuint render_buffers[BUFFER_COUNT];
+  GLuint textures[BUFFER_COUNT];
 } ShaderProgram;
 
 typedef GLFWwindow Window;