First try for GL drawing. Scene 00 cannot render after scene01_init.

4 files changed, 154 insertions, 25 deletions

diff --git a/src/main.c b/src/main.c
index a73bf44..3f18052 100644
--- a/src/main.c
+++ b/src/main.c
@@ -77,28 +77,10 @@ int main(void)
 	if ( ge.sdl_target == NULL ) return 9;
 	ge.raw_target = malloc(256*256*4);
 	if ( ge.raw_target == NULL ) return 10;
-	ge.gl_ctx = SDL_GL_CreateContext(ge.sdl_win);
-	if ( ge.gl_ctx == NULL ) return 11;
 
-	
 	// Initialize OpenGL
-	glShadeModel(GL_SMOOTH);
-	glClearDepth(1.0f);
-	glEnable(GL_DEPTH_TEST);
-	glDepthFunc(GL_LEQUAL);
-	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
-	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
-
-	glDisable(GL_TEXTURE_2D);
-	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
-	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
-	glEnable(GL_CULL_FACE);
-	glCullFace(GL_FRONT);
-	glViewport(0, 0, (GLsizei)256, (GLsizei)256);
-	glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0f, 1.0f, 0.1f, 100.0f); // 1.0f==ratio
-	glMatrixMode(GL_MODELVIEW);  glLoadIdentity();
+	ge.gl_ctx = SDL_GL_CreateContext(ge.sdl_win);
+	if ( ge.gl_ctx == NULL ) return 11;
 
 	// Main libcaca loop for caca window (OpenGL could be used in sceneN_next())
 	ge.framecount=0;
diff --git a/src/main.h b/src/main.h
index b2b0a6e..1ff41ec 100644
--- a/src/main.h
+++ b/src/main.h
@@ -1,6 +1,8 @@
 #ifndef MAIN_H_INCLUDED
 #define MAIN_H_INCLUDED
 
+#define GL_GLEXT_PROTOTYPES
+
 #include <caca.h>
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_opengl.h>
diff --git a/src/scene01.c b/src/scene01.c
index 2b3e9f5..80cbae2 100644
--- a/src/scene01.c
+++ b/src/scene01.c
@@ -19,11 +19,140 @@
  */
 #include "scene01.h"
 
+// Mostly inspired by CC0 https://gist.github.com/koute/7391344
+typedef float t_mat4x4[16];
+
+static inline void mat4x4_ortho( t_mat4x4 out, float left, float right, float bottom, float top, float znear, float zfar )
+{
+    #define T(a, b) (a * 4 + b)
+
+    out[T(0,0)] = 2.0f / (right - left);
+    out[T(0,1)] = 0.0f;
+    out[T(0,2)] = 0.0f;
+    out[T(0,3)] = 0.0f;
+
+    out[T(1,1)] = 2.0f / (top - bottom);
+    out[T(1,0)] = 0.0f;
+    out[T(1,2)] = 0.0f;
+    out[T(1,3)] = 0.0f;
+
+    out[T(2,2)] = -2.0f / (zfar - znear);
+    out[T(2,0)] = 0.0f;
+    out[T(2,1)] = 0.0f;
+    out[T(2,3)] = 0.0f;
+
+    out[T(3,0)] = -(right + left) / (right - left);
+    out[T(3,1)] = -(top + bottom) / (top - bottom);
+    out[T(3,2)] = -(zfar + znear) / (zfar - znear);
+    out[T(3,3)] = 1.0f;
+
+    #undef T
+}
+
+static const char * vertex_shader =
+    "#version 130\n"
+    "in vec2 i_position;\n"
+    "in vec4 i_color;\n"
+    "out vec4 v_color;\n"
+    "uniform mat4 u_projection_matrix;\n"
+    "void main() {\n"
+    "    v_color = i_color;\n"
+    "    gl_Position = u_projection_matrix * vec4( i_position, 0.0, 1.0 );\n"
+    "}\n";
+
+static const char * fragment_shader =
+    "#version 130\n"
+    "in vec4 v_color;\n"
+    "out vec4 o_color;\n"
+    "void main() {\n"
+    "    o_color = v_color;\n"
+    "}\n";
+
+typedef enum t_attrib_id
+{
+    attrib_position,
+    attrib_color
+} t_attrib_id;
+
 int scene01_init(graphical_env_t *ge, scene01_env_t *se) {
+	int width = 256, height = 256;
+    GLuint vs, fs, program;
+
+    vs = glCreateShader( GL_VERTEX_SHADER );
+    fs = glCreateShader( GL_FRAGMENT_SHADER );
+
+    int length = strlen( vertex_shader );
+    glShaderSource( vs, 1, ( const GLchar ** )&vertex_shader, &length );
+    glCompileShader( vs );
+
+    GLint status;
+    glGetShaderiv( vs, GL_COMPILE_STATUS, &status );
+    if( status == GL_FALSE )
+    {
+        fprintf( stderr, "vertex shader compilation failed\n" );
+        return 1;
+    }
+
+    length = strlen( fragment_shader );
+    glShaderSource( fs, 1, ( const GLchar ** )&fragment_shader, &length );
+    glCompileShader( fs );
+
+    glGetShaderiv( fs, GL_COMPILE_STATUS, &status );
+    if( status == GL_FALSE )
+    {
+        fprintf( stderr, "fragment shader compilation failed\n" );
+        return 1;
+    }
+
+    program = glCreateProgram();
+    glAttachShader( program, vs );
+    glAttachShader( program, fs );
+
+    glBindAttribLocation( program, attrib_position, "i_position" );
+    glBindAttribLocation( program, attrib_color, "i_color" );
+    glLinkProgram( program );
+
+    glUseProgram( program );
+
+    glDisable( GL_DEPTH_TEST );
+    //glClearColor( 0.5, 0.0, 0.0, 0.0 );
+    glClearColor( 0.5, 0.5, 0.0, 0.0 );
+    glViewport( 0, 0, width, height );
+
+    GLuint vbo;
+
+    glGenVertexArrays( 1, &(se->vao) );
+    glGenBuffers( 1, &vbo );
+    glBindVertexArray( se->vao );
+    glBindBuffer( GL_ARRAY_BUFFER, vbo );
+
+    glEnableVertexAttribArray( attrib_position );
+    glEnableVertexAttribArray( attrib_color );
+
+    glVertexAttribPointer( attrib_color, 4, GL_FLOAT, GL_FALSE, sizeof( float ) * 6, 0 );
+    glVertexAttribPointer( attrib_position, 2, GL_FLOAT, GL_FALSE, sizeof( float ) * 6, ( void * )(4 * sizeof(float)) );
+
+    const GLfloat g_vertex_buffer_data[] = {
+    /*  R, G, B, A, X, Y  */
+        1, 0, 0, 1, 0, 0,
+        0, 1, 0, 1, width, 0,
+        0, 0, 1, 1, width, height,
+
+        1, 0, 0, 1, 0, 0,
+        0, 0, 1, 1, width, height,
+        1, 1, 1, 1, 0, height
+    };
+
+    glBufferData( GL_ARRAY_BUFFER, sizeof( g_vertex_buffer_data ), g_vertex_buffer_data, GL_STATIC_DRAW );
+
+    t_mat4x4 projection_matrix;
+    mat4x4_ortho( projection_matrix, 0.0f, (float)width, (float)height, 0.0f, 0.0f, 100.0f );
+    glUniformMatrix4fv( glGetUniformLocation( program, "u_projection_matrix" ), 1, GL_FALSE, projection_matrix );
 	return 0;
 }
 
 void scene01_free(graphical_env_t *ge, scene01_env_t *se) {
+	//FIXME scene00 cannot be rendered coorectly after scene01_init done once
 }
 
 int scene01_next(graphical_env_t *ge, scene01_env_t *se) {
@@ -31,13 +160,29 @@ int scene01_next(graphical_env_t *ge, scene01_env_t *se) {
 	caca_canvas_t *cv = ge->cv;
 	int w = ge->w, h = ge->h;
 	Uint32 frame = ge->sc_framecount;
+	SDL_Renderer *r = ge->sdl_rndr;
+	// Locals
+	int res;
+
+	// Render all the stuff on target texture
+	//SDL_SetRenderTarget(r, ge->sdl_target);
+
+	glClear( GL_COLOR_BUFFER_BIT );
+	glBindVertexArray( se->vao );
+	glDrawArrays( GL_TRIANGLES, 0, 6 );
+	SDL_GL_SwapWindow( ge->sdl_win );
 
-	//XXX remove me
-	((Uint32 *)ge->raw_target)[frame%(256*256)]=frame<<((frame%3)*8);
+	// Copy the SDL screen to SDL debug window (and display it, not mandatory)
+	//SDL_SetRenderTarget(r, NULL);
+	//SDL_RenderCopy(r, ge->sdl_target, NULL, NULL);
+	//SDL_RenderPresent(r);
+	
+	// Download the rendered texture from videocard to main memory
+	res = SDL_RenderReadPixels(r, NULL, 0, ge->raw_target, 256*4);
 
-	caca_clear_canvas(cv);
+	// "convert" the raw pixel stream to ASCII art on caca canevas
 	caca_set_dither_gamma(ge->d, (100-frame%100)/100.0);
-	caca_dither_bitmap(cv, 0, 0, w, h, ge->d, ge->raw_target);
+	if ( res == 0 ) caca_dither_bitmap(cv, 0, 0, w, h, ge->d, ge->raw_target);
 
 	caca_set_color_ansi(cv, CACA_WHITE, CACA_BLACK);
 	caca_put_str(cv, (w-17)/2, h/2, "This is a message");
diff --git a/src/scene01.h b/src/scene01.h
index 1f22de7..ecad8df 100644
--- a/src/scene01.h
+++ b/src/scene01.h
@@ -3,7 +3,7 @@
 
 #include "main.h"
 typedef struct {
-
+    GLuint vao;
 } scene01_env_t;
 
 int scene01_init(graphical_env_t *ge, scene01_env_t *se);