mirror of
https://github.com/lxsang/meta-rpi-diya.git
synced 2024-09-07 04:04:41 +02:00
211 lines
5.9 KiB
C
211 lines
5.9 KiB
C
// To compile with gcc: (tested on Ubuntu 14.04 64bit):
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// g++ sdl2_opengl.cpp -lSDL2 -lGL
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// To compile with msvc: (tested on Windows 7 64bit)
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// cl sdl2_opengl.cpp /I C:\sdl2path\include /link C:\path\SDL2.lib C:\path\SDL2main.lib /SUBSYSTEM:CONSOLE /NODEFAULTLIB:libcmtd.lib opengl32.lib
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#include <stdio.h>
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#include <stdint.h>
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#include <assert.h>
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#include <SDL2/SDL.h>
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#include <SDL2/SDL_opengl.h>
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#include <GLES/gl.h>
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typedef int32_t i32;
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typedef uint32_t u32;
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typedef int32_t b32;
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#define WinWidth 480
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#define WinHeight 640
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#define VERTEX_SHADER "\
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void main() \
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{ \
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gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; \
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} \
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"
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#define FRAG_SHADER "\
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void main() \
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{ \
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gl_FragColor = vec4(1.0,0.0,0.0,1.0); \
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} \
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"
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GLuint load_shader(c)
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{
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// Create the shaders
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GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
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GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
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GLint Result = GL_FALSE;
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int InfoLogLength;
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char *source;
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char buff[2048];
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// Compile Vertex Shader
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source = VERTEX_SHADER;
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printf("Compiling vertex shader \n");
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glShaderSource(VertexShaderID, 1, &source, NULL);
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glCompileShader(VertexShaderID);
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memset(buff, 0, sizeof(buff));
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// Check Vertex Shader
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glGetShaderiv(VertexShaderID, GL_COMPILE_STATUS, &Result);
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glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
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if (InfoLogLength > 0)
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{
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glGetShaderInfoLog(VertexShaderID, InfoLogLength, NULL, &buff);
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printf("%s\n", buff);
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}
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// Compile Fragment Shader
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source = FRAG_SHADER;
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printf("Compiling frag shader \n");
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glShaderSource(FragmentShaderID, 1, &source, NULL);
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glCompileShader(FragmentShaderID);
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// Check Fragment Shader
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memset(buff, 0, sizeof(buff));
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glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, &Result);
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glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
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if (InfoLogLength > 0)
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{
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glGetShaderInfoLog(FragmentShaderID, InfoLogLength, NULL, buff);
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printf("%s\n", buff);
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}
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// Link the program
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printf("Linking program\n");
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GLuint ProgramID = glCreateProgram();
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glAttachShader(ProgramID, VertexShaderID);
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glAttachShader(ProgramID, FragmentShaderID);
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glLinkProgram(ProgramID);
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// Check the program
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memset(buff, 0, sizeof(buff));
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glGetProgramiv(ProgramID, GL_LINK_STATUS, &Result);
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glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, &InfoLogLength);
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if (InfoLogLength > 0)
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{
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glGetProgramInfoLog(ProgramID, InfoLogLength, NULL, buff);
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printf("Linking: %s\n", buff);
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}
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glDetachShader(ProgramID, VertexShaderID);
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glDetachShader(ProgramID, FragmentShaderID);
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glDeleteShader(VertexShaderID);
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glDeleteShader(FragmentShaderID);
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return ProgramID;
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}
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int main(int ArgCount, char **Args)
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{
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u32 WindowFlags = SDL_WINDOW_OPENGL;
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SDL_Window *Window = SDL_CreateWindow("OpenGL Test", 0, 0, 0, 0, WindowFlags);
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assert(Window);
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SDL_GLContext Context = SDL_GL_CreateContext(Window);
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SDL_SetWindowFullscreen(Window, SDL_WINDOW_FULLSCREEN);
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SDL_DisplayMode DM;
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SDL_GetCurrentDisplayMode(0, &DM);
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printf("Display size %dx%d\n", DM.w, DM.h);
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int Running = 1;
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// openGL part
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GLuint VertexArrayID;
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glGenVertexArrays(1, &VertexArrayID);
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glBindVertexArray(VertexArrayID);
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printf("Vertex Array ID %d\n", VertexArrayID);
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// Create and compile our GLSL program from the shaders
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GLuint programID = load_shader();
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// GLfloat tmp_buffer[9];
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static const GLfloat g_vertex_buffer_data[] = {
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-1.0f,
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-1.0f,
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0.0f,
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1.0f,
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-1.0f,
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0.0f,
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0.0f,
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1.0f,
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0.0f,
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};
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GLuint vertexbuffer;
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GLint currid = -1;
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glGenBuffers(1, &vertexbuffer);
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glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
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glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);
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// printf("Buffer ID %d of size: %d\n", vertexbuffer, sizeof(tmp_buffer));
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// read back buffer data
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// memset(tmp_buffer, 0, sizeof(tmp_buffer));
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/*
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glGetBufferSubData(GL_ARRAY_BUFFER, 0,sizeof(tmp_buffer), tmp_buffer );
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printf("Read back buffer data: \n");
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for(int i=0; i< 9; i++)
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{
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printf("%d: %.2f\n", i, tmp_buffer[i]);
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}
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*/
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glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &currid);
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printf("current id: %d\n",currid);
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while (Running)
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{
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SDL_Event Event;
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while (SDL_PollEvent(&Event))
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{
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if (Event.type == SDL_KEYDOWN)
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{
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switch (Event.key.keysym.sym)
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{
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case SDLK_ESCAPE:
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Running = 0;
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break;
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default:
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break;
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}
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}
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else if (Event.type == SDL_QUIT)
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{
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Running = 0;
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}
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}
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glViewport(0, 0, DM.w, DM.h);
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glClearColor(1.f, 0.f, 1.f, 0.f);
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glClear(GL_COLOR_BUFFER_BIT);
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// Use our shader
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glUseProgram(programID);
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// 1rst attribute buffer : vertices
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glEnableVertexAttribArray(0);
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glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
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glVertexAttribPointer(
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0, // attribute 0. No particular reason for 0, but must match the layout in the shader.
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3, // size
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GL_FLOAT, // type
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GL_FALSE, // normalized?
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0, // stride
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(void *)0 // array buffer offset
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);
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// Draw the triangle !
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glDrawArrays(GL_TRIANGLES, 0, 3); // 3 indices starting at 0 -> 1 triangle
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glDisableVertexAttribArray(0);
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/* Send our triangle data to the pipeline. */
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SDL_GL_SwapWindow(Window);
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}
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// Cleanup VBO
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glDeleteBuffers(1, &vertexbuffer);
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glDeleteVertexArrays(1, &VertexArrayID);
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glDeleteProgram(programID);
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return 0;
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} |