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Diffstat (limited to 'tests/gl_ps_workaround2.c')
| -rw-r--r-- | tests/gl_ps_workaround2.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/tests/gl_ps_workaround2.c b/tests/gl_ps_workaround2.c new file mode 100644 index 00000000..e5bd2fd1 --- /dev/null +++ b/tests/gl_ps_workaround2.c @@ -0,0 +1,230 @@ +/******************************************************************* + * * + * Using SDL With OpenGL * + * * + * Tutorial by Kyle Foley (sdw) * + * * + * http://gpwiki.org/index.php/SDL:Tutorials:Using_SDL_with_OpenGL * + * * + *******************************************************************/ + +/* +THIS WORK, INCLUDING THE SOURCE CODE, DOCUMENTATION +AND RELATED MEDIA AND DATA, IS PLACED INTO THE PUBLIC DOMAIN. + +THE ORIGINAL AUTHOR IS KYLE FOLEY. + +THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY +OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF +MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE, +ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE +RESULTING FROM THE USE, MODIFICATION, OR +REDISTRIBUTION OF THIS SOFTWARE. +*/ + +#if !EMSCRIPTEN +#define USE_GLEW 1 +#endif + +#if USE_GLEW +#include "GL/glew.h" +#endif + +#include "SDL/SDL.h" +#include "SDL/SDL_image.h" +#if !USE_GLEW +#include "SDL/SDL_opengl.h" +#endif + +#include <stdio.h> +#include <string.h> +#include <assert.h> + +void shaders() { +#if USE_GLEW + glewInit(); +#endif + + GLint ok; + + const char *vertexShader = "void main(void) \n" + "{ \n" + " gl_Position = ftransform(); \n" + " gl_TexCoord[0] = gl_MultiTexCoord0; \n" + " gl_FrontColor = gl_Color; \n" + "} \n"; + const char *fragmentShader = "uniform sampler2D tex0; \n" + "void main(void) \n" + "{ \n" + " gl_FragColor = gl_Color * texture2D(tex0, gl_TexCoord[0].xy); \n" + "} \n"; + + GLuint vs = glCreateShader(GL_VERTEX_SHADER); + glShaderSource(vs, 1, &vertexShader, NULL); + glCompileShader(vs); + glGetShaderiv(vs, GL_COMPILE_STATUS, &ok); + assert(ok); + + GLuint fs = glCreateShader(GL_FRAGMENT_SHADER); + glShaderSource(fs, 1, &fragmentShader, NULL); + glCompileShader(fs); + glGetShaderiv(fs, GL_COMPILE_STATUS, &ok); + assert(ok); + + GLuint program = glCreateProgram(); + + glAttachShader(program, vs); + glAttachShader(program, fs); + glLinkProgram(program); + glGetProgramiv(program, GL_LINK_STATUS, &ok); + assert(ok); + + glUseProgram(program); +} + +int main(int argc, char *argv[]) +{ + SDL_Surface *screen; + + // Slightly different SDL initialization + if ( SDL_Init(SDL_INIT_VIDEO) != 0 ) { + printf("Unable to initialize SDL: %s\n", SDL_GetError()); + return 1; + } + + SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); // *new* + + screen = SDL_SetVideoMode( 640, 480, 16, SDL_OPENGL ); // *changed* + if ( !screen ) { + printf("Unable to set video mode: %s\n", SDL_GetError()); + return 1; + } + + // Set the OpenGL state after creating the context with SDL_SetVideoMode + + glClearColor( 0, 0, 0, 0 ); + +#if !EMSCRIPTEN + glEnable( GL_TEXTURE_2D ); // Need this to display a texture XXX unnecessary in OpenGL ES 2.0/WebGL +#endif + + glViewport( 0, 0, 640, 480 ); + + glMatrixMode( GL_PROJECTION ); + GLfloat matrixData[] = { 2.0/640, 0, 0, 0, + 0, -2.0/480, 0, 0, + 0, 0, -1, 0, + -1, 1, 0, 1 }; + glLoadMatrixf(matrixData); // test loadmatrix + + glMatrixMode( GL_MODELVIEW ); + glLoadIdentity(); + + // Load the OpenGL texture + + GLuint texture; // Texture object handle + SDL_Surface *surface; // Gives us the information to make the texture + + if ( (surface = IMG_Load("screenshot.png")) ) { + + // Check that the image's width is a power of 2 + if ( (surface->w & (surface->w - 1)) != 0 ) { + printf("warning: image.bmp's width is not a power of 2\n"); + } + + // Also check if the height is a power of 2 + if ( (surface->h & (surface->h - 1)) != 0 ) { + printf("warning: image.bmp's height is not a power of 2\n"); + } + + // Have OpenGL generate a texture object handle for us + glGenTextures( 1, &texture ); + + // Bind the texture object + glBindTexture( GL_TEXTURE_2D, texture ); + + // Set the texture's stretching properties + glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR ); + glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR ); + + //SDL_LockSurface(surface); + + // Add some greyness + memset(surface->pixels, 0x66, surface->w*surface->h); + + // Edit the texture object's image data using the information SDL_Surface gives us + glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, surface->w, surface->h, 0, + GL_RGBA, GL_UNSIGNED_BYTE, surface->pixels ); + + //SDL_UnlockSurface(surface); + } + else { + printf("SDL could not load image.bmp: %s\n", SDL_GetError()); + SDL_Quit(); + return 1; + } + + // Free the SDL_Surface only if it was successfully created + if ( surface ) { + SDL_FreeSurface( surface ); + } + + // Clear the screen before drawing + glClear( GL_COLOR_BUFFER_BIT ); + + shaders(); + + // Bind the texture to which subsequent calls refer to + glBindTexture( GL_TEXTURE_2D, texture ); + + // Use clientside vertex pointers to render two items. In this test we have each + // attribute in a separate buffer, packed (i.e. stride == 0) + GLfloat vertexData[] = { 10, 10, + 300, 10, + 300, 128, + 10, 128, + 410, 10, + 600, 10, + 630, 200, + 310, 250, + 100, 300, + 300, 300, + 300, 400, + 100, 400 }; + GLfloat textureData[] = { 0, 0, + 1, 0, + 1, 1, + 0, 1, + 0, 0.5, + 1, 0.5, + 1, 1, + 0.5, 1, + 0, 0, + 1, 0, + 1, 1, + 0, 1, }; + + glEnable(GL_TEXTURE_2D); // XXX should be GL_TEXTURE_COORD_ARRAY); and also glEnableClientState! XXX two workarounds here + glTexCoordPointer(2, GL_FLOAT, 0, textureData); + glEnableClientState(GL_VERTEX_ARRAY); + glVertexPointer(2, GL_FLOAT, 0, vertexData); + + glDrawArrays(GL_QUADS, 0, 12); + + glDisableClientState(GL_TEXTURE_COORD_ARRAY); + glDisableClientState(GL_VERTEX_ARRAY); + + SDL_GL_SwapBuffers(); + +#if !EMSCRIPTEN + // Wait for 3 seconds to give us a chance to see the image + SDL_Delay(3000); +#endif + + // Now we can delete the OpenGL texture and close down SDL + glDeleteTextures( 1, &texture ); + + SDL_Quit(); + + return 0; +} |