Main: implement basic 'Hello Triangle' example

CMakeLists.txt

@@ -1,7 +1,14 @@
 cmake_minimum_required(VERSION 3.25)
 project(ssts C)
 
-add_executable(${PROJECT_NAME} main.c)
+set(SOURCE_FILES main.c)
+set(HEADER_FILES )
+set(SHADER_FILES shader.vert shader.frag)
+
+foreach(SHADER IN LISTS SHADER_FILES)
+configure_file(${SHADER} ${CMAKE_CURRENT_BINARY_DIR} COPYONLY)
+endforeach()
+add_executable(${PROJECT_NAME} ${HEADER_FILES} ${SOURCE_FILES} ${SHADER_FILES})
 
 # We need a CMAKE_DIR with some code to find external dependencies
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/")
@@ -9,7 +16,8 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/")
 find_package(OpenGL REQUIRED)
 find_package(GLUT REQUIRED)
 find_package(GLEW REQUIRED)
+find_package(assimp REQUIRED)
 
-include_directories(${PROJECT_NAME} ${OPENGL_INCLUDE_DIRS} ${GLUT_INCLUDE_DIRS} ${GLEW_INCLUDE_DIRS})
+include_directories(${PROJECT_NAME} ${OPENGL_INCLUDE_DIRS} ${GLUT_INCLUDE_DIRS} ${GLEW_INCLUDE_DIRS} ${ASSIMP_INCLUDE_DIRS})
 
-target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES} ${GLUT_LIBRARIES} ${GLEW_LIBRARIES})
+target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES} ${GLUT_LIBRARIES} ${GLEW_LIBRARIES} ${ASSIMP_LIBRARIES})

main.c

@@ -2,17 +2,175 @@
 #include <GL/glew.h>
 #include <GL/freeglut.h>
 
-int main(int argc, char **argv) {
+unsigned int vao;
+unsigned int vbo;
+unsigned int shader_program;
+unsigned int vertex_shader;
+unsigned int fragment_shader;
 
+const char *vertex_shader_location = "./shader.vert";
+const char *fragment_shader_location = "./shader.frag";
+
+float vertices[] = {
+        -0.5f, -0.5f, 0.0f,
+        0.5f, -0.5f, 0.0f,
+        0.0f,  0.5f, 0.0f
+};
+
+int load_shader(const char *path, unsigned int shader) {
+    FILE *fp = fopen(path, "r");
+    int len = 0;
+    char *ftext;
+
+    if (fp == NULL) {
+        fprintf(stderr, "Error: Cannot open file '%s'\n", path);
+        return -1;
+    }
+
+    fseek(fp, 0L, SEEK_END);
+    len = ftell(fp);
+
+    if (len == -1) {
+        fprintf(stderr, "Error: Cannot fetch length of file '%s'\n", path);
+        return -1;
+    }
+
+    fseek(fp, 0L, SEEK_SET);
+
+    ftext = (char *) malloc(len);
+    if (ftext == NULL) {
+        fprintf(stderr, "Error: Cannot allocate enough memory for file's contents '%s'\n", path);
+        return -1;
+    }
+
+    fread(ftext, sizeof(char), len, fp);
+    fclose(fp);
+
+    glShaderSource(shader, 1, (const char **) &ftext,  &len);
+    glCompileShader(shader);
+
+    int success;
+    glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
+
+    if (success != GL_TRUE) {
+        int log_length;
+        glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &log_length);
+
+        char log[log_length];
+        glGetShaderInfoLog(shader, log_length, NULL, log);
+
+        fprintf(stderr, "Shader Compilation Error: %s\n", log);
+        return -1;
+    }
+
+    // RUD
+    free(ftext);
+
+    return 0;
+}
+
+int setup() {
+    vertex_shader = glCreateShader(GL_VERTEX_SHADER);
+    fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
+
+    if (load_shader(vertex_shader_location, vertex_shader) == -1) {
+        return -1;
+    }
+
+    if (load_shader(fragment_shader_location, fragment_shader) == -1) {
+        return -1;
+    }
+
+    shader_program = glCreateProgram();
+    glAttachShader(shader_program, vertex_shader);
+    glAttachShader(shader_program, fragment_shader);
+    glLinkProgram(shader_program);
+
+    int success;
+    glGetProgramiv(shader_program, GL_LINK_STATUS, &success);
+
+    if (success != GL_TRUE) {
+        int log_length;
+        glGetProgramiv(shader_program, GL_INFO_LOG_LENGTH, &log_length);
+
+        char log[log_length];
+        glGetProgramInfoLog(shader_program, log_length, NULL, log);
+
+        fprintf(stderr, "Shader Compilation Error: %s\n", log);
+        return -1;
+    }
+
+    glGenVertexArrays(1, &vao);
+    glGenBuffers(1, &vbo);
+
+    // RUD
+    glDeleteShader(vertex_shader);
+    glDeleteShader(fragment_shader);
+
+    return 0;
+}
+
+int post_setup() {
+    glBindVertexArray(vao);
+
+    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*) 0);
+    glEnableVertexAttribArray(0);
+
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+    glBindVertexArray(0);
+}
+
+void keyboard(unsigned char key, int x, int y) {
+    switch (key) {
+        case '\x1B':
+        {
+            exit(EXIT_SUCCESS);
+            break;
+        }
+    }
+}
+
+
+void display() {
+    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    glUseProgram(shader_program);
+    glBindVertexArray(vao);
+
+    glDrawArrays(GL_TRIANGLES, 0, 3);
+
+    glutSwapBuffers();
+}
+
+int main(int argc, char **argv) {
     glutInit(&argc, argv);
     glutCreateWindow("Simple Space Time Simulator");
     GLenum err = glewInit();
     if (err != GLEW_OK) {
         fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
+        return EXIT_FAILURE;
+    }
+
+    fprintf(stdout, "Status: using with GLEW %s\n", glewGetString(GLEW_VERSION));
+
+    glutKeyboardFunc(&keyboard);
+    glutDisplayFunc(&display);
+
+    if (setup() == -1) {
+        fprintf(stderr, "Error: Failed to setup\n");
         return -1;
     }
 
-    fprintf(stdout, "Status: using GLEW %s\n", glewGetString(GLEW_VERSION));
-
-    return 0;
+    if (post_setup() == -1) {
+        fprintf(stderr, "Error: Failed to post-setup\n");
+        return -1;
+    }
+
+    glutMainLoop();
+
+    return EXIT_SUCCESS;
 }

shader.frag

@@ -0,0 +1,6 @@
+#version 330 core
+out vec4 FragColor;
+
+void main() {
+    FragColor = vec4(1.0f, 1.0f, 1.0f, 1.0f);
+}

shader.vert

@@ -0,0 +1,6 @@
+#version 330 core
+layout (location = 0) in vec3 pos;
+
+void main() {
+    gl_Position = vec4(pos.x, pos.y, pos.z, 1.0f);
+}