mirror of
https://github.com/Relintai/sdl2_frt.git
synced 2024-11-21 20:47:19 +01:00
501 lines
15 KiB
C
501 lines
15 KiB
C
/*
|
|
Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
|
|
|
|
This software is provided 'as-is', without any express or implied
|
|
warranty. In no event will the authors be held liable for any damages
|
|
arising from the use of this software.
|
|
|
|
Permission is granted to anyone to use this software for any purpose,
|
|
including commercial applications, and to alter it and redistribute it
|
|
freely.
|
|
*/
|
|
/* This is a simple example of using GLSL shaders with SDL */
|
|
|
|
#include "SDL.h"
|
|
|
|
#ifdef HAVE_OPENGL
|
|
|
|
#include "SDL_opengl.h"
|
|
|
|
|
|
static SDL_bool shaders_supported;
|
|
static int current_shader = 0;
|
|
|
|
enum {
|
|
SHADER_COLOR,
|
|
SHADER_TEXTURE,
|
|
SHADER_TEXCOORDS,
|
|
NUM_SHADERS
|
|
};
|
|
|
|
typedef struct {
|
|
GLhandleARB program;
|
|
GLhandleARB vert_shader;
|
|
GLhandleARB frag_shader;
|
|
const char *vert_source;
|
|
const char *frag_source;
|
|
} ShaderData;
|
|
|
|
static ShaderData shaders[NUM_SHADERS] = {
|
|
|
|
/* SHADER_COLOR */
|
|
{ 0, 0, 0,
|
|
/* vertex shader */
|
|
"varying vec4 v_color;\n"
|
|
"\n"
|
|
"void main()\n"
|
|
"{\n"
|
|
" gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
|
|
" v_color = gl_Color;\n"
|
|
"}",
|
|
/* fragment shader */
|
|
"varying vec4 v_color;\n"
|
|
"\n"
|
|
"void main()\n"
|
|
"{\n"
|
|
" gl_FragColor = v_color;\n"
|
|
"}"
|
|
},
|
|
|
|
/* SHADER_TEXTURE */
|
|
{ 0, 0, 0,
|
|
/* vertex shader */
|
|
"varying vec4 v_color;\n"
|
|
"varying vec2 v_texCoord;\n"
|
|
"\n"
|
|
"void main()\n"
|
|
"{\n"
|
|
" gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
|
|
" v_color = gl_Color;\n"
|
|
" v_texCoord = vec2(gl_MultiTexCoord0);\n"
|
|
"}",
|
|
/* fragment shader */
|
|
"varying vec4 v_color;\n"
|
|
"varying vec2 v_texCoord;\n"
|
|
"uniform sampler2D tex0;\n"
|
|
"\n"
|
|
"void main()\n"
|
|
"{\n"
|
|
" gl_FragColor = texture2D(tex0, v_texCoord) * v_color;\n"
|
|
"}"
|
|
},
|
|
|
|
/* SHADER_TEXCOORDS */
|
|
{ 0, 0, 0,
|
|
/* vertex shader */
|
|
"varying vec2 v_texCoord;\n"
|
|
"\n"
|
|
"void main()\n"
|
|
"{\n"
|
|
" gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
|
|
" v_texCoord = vec2(gl_MultiTexCoord0);\n"
|
|
"}",
|
|
/* fragment shader */
|
|
"varying vec2 v_texCoord;\n"
|
|
"\n"
|
|
"void main()\n"
|
|
"{\n"
|
|
" vec4 color;\n"
|
|
" vec2 delta;\n"
|
|
" float dist;\n"
|
|
"\n"
|
|
" delta = vec2(0.5, 0.5) - v_texCoord;\n"
|
|
" dist = dot(delta, delta);\n"
|
|
"\n"
|
|
" color.r = v_texCoord.x;\n"
|
|
" color.g = v_texCoord.x * v_texCoord.y;\n"
|
|
" color.b = v_texCoord.y;\n"
|
|
" color.a = 1.0 - (dist * 4.0);\n"
|
|
" gl_FragColor = color;\n"
|
|
"}"
|
|
},
|
|
};
|
|
|
|
static PFNGLATTACHOBJECTARBPROC glAttachObjectARB;
|
|
static PFNGLCOMPILESHADERARBPROC glCompileShaderARB;
|
|
static PFNGLCREATEPROGRAMOBJECTARBPROC glCreateProgramObjectARB;
|
|
static PFNGLCREATESHADEROBJECTARBPROC glCreateShaderObjectARB;
|
|
static PFNGLDELETEOBJECTARBPROC glDeleteObjectARB;
|
|
static PFNGLGETINFOLOGARBPROC glGetInfoLogARB;
|
|
static PFNGLGETOBJECTPARAMETERIVARBPROC glGetObjectParameterivARB;
|
|
static PFNGLGETUNIFORMLOCATIONARBPROC glGetUniformLocationARB;
|
|
static PFNGLLINKPROGRAMARBPROC glLinkProgramARB;
|
|
static PFNGLSHADERSOURCEARBPROC glShaderSourceARB;
|
|
static PFNGLUNIFORM1IARBPROC glUniform1iARB;
|
|
static PFNGLUSEPROGRAMOBJECTARBPROC glUseProgramObjectARB;
|
|
|
|
static SDL_bool CompileShader(GLhandleARB shader, const char *source)
|
|
{
|
|
GLint status;
|
|
|
|
glShaderSourceARB(shader, 1, &source, NULL);
|
|
glCompileShaderARB(shader);
|
|
glGetObjectParameterivARB(shader, GL_OBJECT_COMPILE_STATUS_ARB, &status);
|
|
if (status == 0) {
|
|
GLint length;
|
|
char *info;
|
|
|
|
glGetObjectParameterivARB(shader, GL_OBJECT_INFO_LOG_LENGTH_ARB, &length);
|
|
info = SDL_stack_alloc(char, length+1);
|
|
glGetInfoLogARB(shader, length, NULL, info);
|
|
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to compile shader:\n%s\n%s", source, info);
|
|
SDL_stack_free(info);
|
|
|
|
return SDL_FALSE;
|
|
} else {
|
|
return SDL_TRUE;
|
|
}
|
|
}
|
|
|
|
static SDL_bool CompileShaderProgram(ShaderData *data)
|
|
{
|
|
const int num_tmus_bound = 4;
|
|
int i;
|
|
GLint location;
|
|
|
|
glGetError();
|
|
|
|
/* Create one program object to rule them all */
|
|
data->program = glCreateProgramObjectARB();
|
|
|
|
/* Create the vertex shader */
|
|
data->vert_shader = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB);
|
|
if (!CompileShader(data->vert_shader, data->vert_source)) {
|
|
return SDL_FALSE;
|
|
}
|
|
|
|
/* Create the fragment shader */
|
|
data->frag_shader = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);
|
|
if (!CompileShader(data->frag_shader, data->frag_source)) {
|
|
return SDL_FALSE;
|
|
}
|
|
|
|
/* ... and in the darkness bind them */
|
|
glAttachObjectARB(data->program, data->vert_shader);
|
|
glAttachObjectARB(data->program, data->frag_shader);
|
|
glLinkProgramARB(data->program);
|
|
|
|
/* Set up some uniform variables */
|
|
glUseProgramObjectARB(data->program);
|
|
for (i = 0; i < num_tmus_bound; ++i) {
|
|
char tex_name[5];
|
|
SDL_snprintf(tex_name, SDL_arraysize(tex_name), "tex%d", i);
|
|
location = glGetUniformLocationARB(data->program, tex_name);
|
|
if (location >= 0) {
|
|
glUniform1iARB(location, i);
|
|
}
|
|
}
|
|
glUseProgramObjectARB(0);
|
|
|
|
return (glGetError() == GL_NO_ERROR) ? SDL_TRUE : SDL_FALSE;
|
|
}
|
|
|
|
static void DestroyShaderProgram(ShaderData *data)
|
|
{
|
|
if (shaders_supported) {
|
|
glDeleteObjectARB(data->vert_shader);
|
|
glDeleteObjectARB(data->frag_shader);
|
|
glDeleteObjectARB(data->program);
|
|
}
|
|
}
|
|
|
|
static SDL_bool InitShaders()
|
|
{
|
|
int i;
|
|
|
|
/* Check for shader support */
|
|
shaders_supported = SDL_FALSE;
|
|
if (SDL_GL_ExtensionSupported("GL_ARB_shader_objects") &&
|
|
SDL_GL_ExtensionSupported("GL_ARB_shading_language_100") &&
|
|
SDL_GL_ExtensionSupported("GL_ARB_vertex_shader") &&
|
|
SDL_GL_ExtensionSupported("GL_ARB_fragment_shader")) {
|
|
glAttachObjectARB = (PFNGLATTACHOBJECTARBPROC) SDL_GL_GetProcAddress("glAttachObjectARB");
|
|
glCompileShaderARB = (PFNGLCOMPILESHADERARBPROC) SDL_GL_GetProcAddress("glCompileShaderARB");
|
|
glCreateProgramObjectARB = (PFNGLCREATEPROGRAMOBJECTARBPROC) SDL_GL_GetProcAddress("glCreateProgramObjectARB");
|
|
glCreateShaderObjectARB = (PFNGLCREATESHADEROBJECTARBPROC) SDL_GL_GetProcAddress("glCreateShaderObjectARB");
|
|
glDeleteObjectARB = (PFNGLDELETEOBJECTARBPROC) SDL_GL_GetProcAddress("glDeleteObjectARB");
|
|
glGetInfoLogARB = (PFNGLGETINFOLOGARBPROC) SDL_GL_GetProcAddress("glGetInfoLogARB");
|
|
glGetObjectParameterivARB = (PFNGLGETOBJECTPARAMETERIVARBPROC) SDL_GL_GetProcAddress("glGetObjectParameterivARB");
|
|
glGetUniformLocationARB = (PFNGLGETUNIFORMLOCATIONARBPROC) SDL_GL_GetProcAddress("glGetUniformLocationARB");
|
|
glLinkProgramARB = (PFNGLLINKPROGRAMARBPROC) SDL_GL_GetProcAddress("glLinkProgramARB");
|
|
glShaderSourceARB = (PFNGLSHADERSOURCEARBPROC) SDL_GL_GetProcAddress("glShaderSourceARB");
|
|
glUniform1iARB = (PFNGLUNIFORM1IARBPROC) SDL_GL_GetProcAddress("glUniform1iARB");
|
|
glUseProgramObjectARB = (PFNGLUSEPROGRAMOBJECTARBPROC) SDL_GL_GetProcAddress("glUseProgramObjectARB");
|
|
if (glAttachObjectARB &&
|
|
glCompileShaderARB &&
|
|
glCreateProgramObjectARB &&
|
|
glCreateShaderObjectARB &&
|
|
glDeleteObjectARB &&
|
|
glGetInfoLogARB &&
|
|
glGetObjectParameterivARB &&
|
|
glGetUniformLocationARB &&
|
|
glLinkProgramARB &&
|
|
glShaderSourceARB &&
|
|
glUniform1iARB &&
|
|
glUseProgramObjectARB) {
|
|
shaders_supported = SDL_TRUE;
|
|
}
|
|
}
|
|
|
|
if (!shaders_supported) {
|
|
return SDL_FALSE;
|
|
}
|
|
|
|
/* Compile all the shaders */
|
|
for (i = 0; i < NUM_SHADERS; ++i) {
|
|
if (!CompileShaderProgram(&shaders[i])) {
|
|
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to compile shader!\n");
|
|
return SDL_FALSE;
|
|
}
|
|
}
|
|
|
|
/* We're done! */
|
|
return SDL_TRUE;
|
|
}
|
|
|
|
static void QuitShaders()
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < NUM_SHADERS; ++i) {
|
|
DestroyShaderProgram(&shaders[i]);
|
|
}
|
|
}
|
|
|
|
/* Quick utility function for texture creation */
|
|
static int
|
|
power_of_two(int input)
|
|
{
|
|
int value = 1;
|
|
|
|
while (value < input) {
|
|
value <<= 1;
|
|
}
|
|
return value;
|
|
}
|
|
|
|
GLuint
|
|
SDL_GL_LoadTexture(SDL_Surface * surface, GLfloat * texcoord)
|
|
{
|
|
GLuint texture;
|
|
int w, h;
|
|
SDL_Surface *image;
|
|
SDL_Rect area;
|
|
SDL_BlendMode saved_mode;
|
|
|
|
/* Use the surface width and height expanded to powers of 2 */
|
|
w = power_of_two(surface->w);
|
|
h = power_of_two(surface->h);
|
|
texcoord[0] = 0.0f; /* Min X */
|
|
texcoord[1] = 0.0f; /* Min Y */
|
|
texcoord[2] = (GLfloat) surface->w / w; /* Max X */
|
|
texcoord[3] = (GLfloat) surface->h / h; /* Max Y */
|
|
|
|
image = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h, 32,
|
|
#if SDL_BYTEORDER == SDL_LIL_ENDIAN /* OpenGL RGBA masks */
|
|
0x000000FF,
|
|
0x0000FF00, 0x00FF0000, 0xFF000000
|
|
#else
|
|
0xFF000000,
|
|
0x00FF0000, 0x0000FF00, 0x000000FF
|
|
#endif
|
|
);
|
|
if (image == NULL) {
|
|
return 0;
|
|
}
|
|
|
|
/* Save the alpha blending attributes */
|
|
SDL_GetSurfaceBlendMode(surface, &saved_mode);
|
|
SDL_SetSurfaceBlendMode(surface, SDL_BLENDMODE_NONE);
|
|
|
|
/* Copy the surface into the GL texture image */
|
|
area.x = 0;
|
|
area.y = 0;
|
|
area.w = surface->w;
|
|
area.h = surface->h;
|
|
SDL_BlitSurface(surface, &area, image, &area);
|
|
|
|
/* Restore the alpha blending attributes */
|
|
SDL_SetSurfaceBlendMode(surface, saved_mode);
|
|
|
|
/* Create an OpenGL texture for the image */
|
|
glGenTextures(1, &texture);
|
|
glBindTexture(GL_TEXTURE_2D, texture);
|
|
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
|
|
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
|
|
glTexImage2D(GL_TEXTURE_2D,
|
|
0,
|
|
GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image->pixels);
|
|
SDL_FreeSurface(image); /* No longer needed */
|
|
|
|
return texture;
|
|
}
|
|
|
|
/* A general OpenGL initialization function. Sets all of the initial parameters. */
|
|
void InitGL(int Width, int Height) /* We call this right after our OpenGL window is created. */
|
|
{
|
|
GLdouble aspect;
|
|
|
|
glViewport(0, 0, Width, Height);
|
|
glClearColor(0.0f, 0.0f, 0.0f, 0.0f); /* This Will Clear The Background Color To Black */
|
|
glClearDepth(1.0); /* Enables Clearing Of The Depth Buffer */
|
|
glDepthFunc(GL_LESS); /* The Type Of Depth Test To Do */
|
|
glEnable(GL_DEPTH_TEST); /* Enables Depth Testing */
|
|
glShadeModel(GL_SMOOTH); /* Enables Smooth Color Shading */
|
|
|
|
glMatrixMode(GL_PROJECTION);
|
|
glLoadIdentity(); /* Reset The Projection Matrix */
|
|
|
|
aspect = (GLdouble)Width / Height;
|
|
glOrtho(-3.0, 3.0, -3.0 / aspect, 3.0 / aspect, 0.0, 1.0);
|
|
|
|
glMatrixMode(GL_MODELVIEW);
|
|
}
|
|
|
|
/* The main drawing function. */
|
|
void DrawGLScene(SDL_Window *window, GLuint texture, GLfloat * texcoord)
|
|
{
|
|
/* Texture coordinate lookup, to make it simple */
|
|
enum {
|
|
MINX,
|
|
MINY,
|
|
MAXX,
|
|
MAXY
|
|
};
|
|
|
|
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); /* Clear The Screen And The Depth Buffer */
|
|
glLoadIdentity(); /* Reset The View */
|
|
|
|
glTranslatef(-1.5f,0.0f,0.0f); /* Move Left 1.5 Units */
|
|
|
|
/* draw a triangle (in smooth coloring mode) */
|
|
glBegin(GL_POLYGON); /* start drawing a polygon */
|
|
glColor3f(1.0f,0.0f,0.0f); /* Set The Color To Red */
|
|
glVertex3f( 0.0f, 1.0f, 0.0f); /* Top */
|
|
glColor3f(0.0f,1.0f,0.0f); /* Set The Color To Green */
|
|
glVertex3f( 1.0f,-1.0f, 0.0f); /* Bottom Right */
|
|
glColor3f(0.0f,0.0f,1.0f); /* Set The Color To Blue */
|
|
glVertex3f(-1.0f,-1.0f, 0.0f); /* Bottom Left */
|
|
glEnd(); /* we're done with the polygon (smooth color interpolation) */
|
|
|
|
glTranslatef(3.0f,0.0f,0.0f); /* Move Right 3 Units */
|
|
|
|
/* Enable blending */
|
|
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
|
|
glEnable(GL_BLEND);
|
|
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
|
|
|
|
/* draw a textured square (quadrilateral) */
|
|
glEnable(GL_TEXTURE_2D);
|
|
glBindTexture(GL_TEXTURE_2D, texture);
|
|
glColor3f(1.0f,1.0f,1.0f);
|
|
if (shaders_supported) {
|
|
glUseProgramObjectARB(shaders[current_shader].program);
|
|
}
|
|
|
|
glBegin(GL_QUADS); /* start drawing a polygon (4 sided) */
|
|
glTexCoord2f(texcoord[MINX], texcoord[MINY]);
|
|
glVertex3f(-1.0f, 1.0f, 0.0f); /* Top Left */
|
|
glTexCoord2f(texcoord[MAXX], texcoord[MINY]);
|
|
glVertex3f( 1.0f, 1.0f, 0.0f); /* Top Right */
|
|
glTexCoord2f(texcoord[MAXX], texcoord[MAXY]);
|
|
glVertex3f( 1.0f,-1.0f, 0.0f); /* Bottom Right */
|
|
glTexCoord2f(texcoord[MINX], texcoord[MAXY]);
|
|
glVertex3f(-1.0f,-1.0f, 0.0f); /* Bottom Left */
|
|
glEnd(); /* done with the polygon */
|
|
|
|
if (shaders_supported) {
|
|
glUseProgramObjectARB(0);
|
|
}
|
|
glDisable(GL_TEXTURE_2D);
|
|
|
|
/* swap buffers to display, since we're double buffered. */
|
|
SDL_GL_SwapWindow(window);
|
|
}
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
int done;
|
|
SDL_Window *window;
|
|
SDL_Surface *surface;
|
|
GLuint texture;
|
|
GLfloat texcoords[4];
|
|
|
|
/* Enable standard application logging */
|
|
SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
|
|
|
|
/* Initialize SDL for video output */
|
|
if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
|
|
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to initialize SDL: %s\n", SDL_GetError());
|
|
exit(1);
|
|
}
|
|
|
|
/* Create a 640x480 OpenGL screen */
|
|
window = SDL_CreateWindow( "Shader Demo", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_OPENGL );
|
|
if ( !window ) {
|
|
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to create OpenGL window: %s\n", SDL_GetError());
|
|
SDL_Quit();
|
|
exit(2);
|
|
}
|
|
|
|
if ( !SDL_GL_CreateContext(window)) {
|
|
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to create OpenGL context: %s\n", SDL_GetError());
|
|
SDL_Quit();
|
|
exit(2);
|
|
}
|
|
|
|
surface = SDL_LoadBMP("icon.bmp");
|
|
if ( ! surface ) {
|
|
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to load icon.bmp: %s\n", SDL_GetError());
|
|
SDL_Quit();
|
|
exit(3);
|
|
}
|
|
texture = SDL_GL_LoadTexture(surface, texcoords);
|
|
SDL_FreeSurface(surface);
|
|
|
|
/* Loop, drawing and checking events */
|
|
InitGL(640, 480);
|
|
if (InitShaders()) {
|
|
SDL_Log("Shaders supported, press SPACE to cycle them.\n");
|
|
} else {
|
|
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Shaders not supported!\n");
|
|
}
|
|
done = 0;
|
|
while ( ! done ) {
|
|
DrawGLScene(window, texture, texcoords);
|
|
|
|
/* This could go in a separate function */
|
|
{ SDL_Event event;
|
|
while ( SDL_PollEvent(&event) ) {
|
|
if ( event.type == SDL_QUIT ) {
|
|
done = 1;
|
|
}
|
|
if ( event.type == SDL_KEYDOWN ) {
|
|
if ( event.key.keysym.sym == SDLK_SPACE ) {
|
|
current_shader = (current_shader + 1) % NUM_SHADERS;
|
|
}
|
|
if ( event.key.keysym.sym == SDLK_ESCAPE ) {
|
|
done = 1;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
QuitShaders();
|
|
SDL_Quit();
|
|
return 1;
|
|
}
|
|
|
|
#else /* HAVE_OPENGL */
|
|
|
|
int
|
|
main(int argc, char *argv[])
|
|
{
|
|
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "No OpenGL support on this system\n");
|
|
return 1;
|
|
}
|
|
|
|
#endif /* HAVE_OPENGL */
|
|
|
|
/* vi: set ts=4 sw=4 expandtab: */
|