Add triangle rendering w/ shader recompilation

5 files changed, 123 insertions, 7 deletions

diff --git a/Makefile b/Makefile
index e7770ac..d1d5630 100644
--- a/Makefile
+++ b/Makefile
@@ -3,10 +3,13 @@
 
 # Source code location and files to watch for changes.
 SRC_DIR        := src
+SHADERS_DIR    := shaders
 SRC_MAIN       := $(SRC_DIR)/main.c
 SRC_APP        := $(SRC_DIR)/app.c
 WATCH_SRC      := $(wildcard $(SRC_DIR)/*.c)
 WATCH_SRC      += $(wildcard $(SRC_DIR)/*.h)
+WATCH_SRC      += $(wildcard $(SHADERS_DIR)/*.vert)
+WATCH_SRC      += $(wildcard $(SHADERS_DIR)/*.frag)
 
 # Output library names and executables.
 BIN_NAME       := app
diff --git a/shaders/triangle.frag b/shaders/triangle.frag
new file mode 100644
index 0000000..e8bde66
--- /dev/null
+++ b/shaders/triangle.frag
@@ -0,0 +1,5 @@
+#version 330 core
+out vec4 frag_col;
+void main() {
+    frag_col = vec4(0.8f, 0.8f, 0.8f, 1.0f);
+}
diff --git a/shaders/triangle.vert b/shaders/triangle.vert
new file mode 100644
index 0000000..d5168a8
--- /dev/null
+++ b/shaders/triangle.vert
@@ -0,0 +1,5 @@
+#version 330 core
+layout (location = 0) in vec3 vertex;
+void main() {
+    gl_Position = vec4(vertex.x, vertex.y, vertex.z, 1.0);
+}
diff --git a/src/app.c b/src/app.c
index 99f5cff..08ca7f2 100644
--- a/src/app.c
+++ b/src/app.c
@@ -1,6 +1,62 @@
 #include "app.h"
 #include "platform.h"
 
+bool
+compile_shaders(const char *vert, const char *frag, u32 *handle,
+        PlatformAPI platform) {
+    int success = 0;
+    char memory[MB(1)] = {0}; // Memory for reading shader files
+
+    // Initialize shader handles.
+    u32 vert_handle = glCreateShader(GL_VERTEX_SHADER);
+    u32 frag_handle = glCreateShader(GL_FRAGMENT_SHADER);
+
+    // Vertex shader.
+    {
+        platform.read_file(vert, memory);
+        const char * source = memory;
+        glShaderSource(vert_handle, 1, &source, NULL);
+        glCompileShader(vert_handle);
+        glGetShaderiv(vert_handle, GL_COMPILE_STATUS, &success);
+        if (!success) {
+            glDeleteShader(vert_handle);
+            glDeleteShader(frag_handle);
+            return false;
+        }
+    }
+
+    // Fragment shader.
+    {
+        platform.read_file(frag, memory);
+        const char * source = memory;
+        glShaderSource(frag_handle, 1, &source, NULL);
+        glCompileShader(frag_handle);
+        glGetShaderiv(frag_handle, GL_COMPILE_STATUS, &success);
+        if (!success) {
+            glDeleteShader(vert_handle);
+            glDeleteShader(frag_handle);
+            return false;
+        }
+    }
+
+    // Program linkage.
+    *handle = glCreateProgram();
+    glAttachShader(*handle, vert_handle);
+    glAttachShader(*handle, frag_handle);
+    glLinkProgram(*handle);
+    glGetProgramiv(*handle, GL_LINK_STATUS, &success);
+    if(!success) {
+        glDeleteProgram(*handle);
+        glDeleteShader(vert_handle);
+        glDeleteShader(frag_handle);
+        return false;
+    }
+    glDeleteShader(vert_handle);
+    glDeleteShader(frag_handle);
+
+    return true;
+}
+
 static inline bool
 app_init(AppState *state, PlatformAPI platform) {
     platform.log("INIT");
@@ -14,7 +70,7 @@ app_init(AppState *state, PlatformAPI platform) {
     glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
     glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
 
-    // // Initialize window.
+    // Initialize window.
     GLFWwindow* window = glfwCreateWindow(400, 300, "Hello MIC", NULL, NULL);
     if (window == NULL) {
         platform.log("ERROR: failed to create GLFW window");
@@ -33,8 +89,47 @@ app_init(AppState *state, PlatformAPI platform) {
     // Initialize viewport.
     glViewport(0, 0, 400, 300);
 
+    // Initialize vertex data.
+    state->vertices[0] = -0.5f;
+    state->vertices[1] = -0.5f;
+    state->vertices[2] = 0.0f;
+    state->vertices[3] = 0.5f;
+    state->vertices[4] = -0.5f;
+    state->vertices[5] = 0.0f;
+    state->vertices[6] = 0.0f;
+    state->vertices[7] = 0.5f;
+    state->vertices[8] = 0.0f;
+
+    // Initialize Vertex Buffer Object (VBO) and Vertex Array Object (VAO).
+    u32 VBO;
+    glGenBuffers(1, &VBO);
+    u32 VAO;
+    glGenVertexArrays(1, &VAO);
+
+    // Bind the VAO before any other binding.
+    glBindVertexArray(VAO);
+
+    // Send vertex data to VBO.
+    glBindBuffer(GL_ARRAY_BUFFER, VBO);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(state->vertices), state->vertices,
+        GL_STATIC_DRAW);
+
+    // Set vertex attribute pointers.
+    glEnableVertexAttribArray(0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), 0);
+
+    // Compile shader program.
+    const char *vert = "shaders/triangle.vert";
+    const char *frag = "shaders/triangle.frag";
+    if (!compile_shaders(vert, frag, &state->shader_program, platform)) {
+        platform.log("WARNING: failed to compile shader program");
+    }
+
     // Initialize application state.
     state->window = window;
+    state->VBO = VBO;
+    state->VAO = VAO;
+
     return true;
 }
 
@@ -46,8 +141,12 @@ app_destroy(AppState *state, PlatformAPI platform) {
 
 static inline void
 app_reload(AppState *state, PlatformAPI platform) {
-    (void)state; // Unused parameter.
     platform.log("RELOAD");
+    const char *vert = "shaders/triangle.vert";
+    const char *frag = "shaders/triangle.frag";
+    if (!compile_shaders(vert, frag, &state->shader_program, platform)) {
+        platform.log("WARNING: failed to compile shader program");
+    }
 }
 
 static inline void
@@ -58,13 +157,13 @@ app_unload(AppState *state, PlatformAPI platform) {
 
 static inline bool
 app_step(AppState *state, PlatformAPI platform) {
-    (void)platform; // Unused parameter.
-    if (glfwWindowShouldClose(state->window)) {
-        return false;
-    }
+    (void)platform; // Unused parameter
 
-    glClearColor(1.0f, 0.0f, 0.4f, 1.0f);
+    glClearColor(0.8f, 0.0f, 0.4f, 1.0f);
     glClear(GL_COLOR_BUFFER_BIT);
+    glUseProgram(state->shader_program);
+    glBindVertexArray(state->VAO);
+    glDrawArrays(GL_TRIANGLES, 0, 3);
 
     glfwSwapBuffers(state->window);
     glfwPollEvents();
diff --git a/src/app.h b/src/app.h
index 613360f..16dc8a5 100644
--- a/src/app.h
+++ b/src/app.h
@@ -10,6 +10,10 @@
 typedef struct AppState {
     // OpenGL
     GLFWwindow *window;
+    f32 vertices[12];
+    u32 VBO;
+    u32 VAO;
+    u32 shader_program;
 } AppState;
 
 // Function pointers for the AppAPI.