我在这里已经阅读了以下问题:Can example "GLImageProcessing" work with multi filters但是,我仍然不明白如何编辑GLImageProcessing的示例代码以支持多个过滤器。这是我现在在Imaging.c的drawGL中执行的代码
有什么帮助吗?
void drawGL(int wide, int high, float val, int mode)
{
GLuint ResultFBO;
GLuint ResultTexture;
static int prevmode = -1;
typedef void (*procfunc)(V2fT2f *, float);
typedef struct {
procfunc func;
procfunc degen;
} Filter;
const Filter filter[] = {
{ brightness },
{ contrast },
{ extrapolate, greyscale },
{ hue },
{ extrapolate, blur }, // The blur could be exaggerated by downsampling to half size
};
#define NUM_FILTERS (sizeof(filter)/sizeof(filter[0]))
rt_assert(mode < NUM_FILTERS);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrthof(0, wide, 0, high, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glScalef(wide, high, 1);
glBindTexture(GL_TEXTURE_2D, Input.texID);
// Remember the FBO being used for the display framebuffer
glGetIntegerv(GL_FRAMEBUFFER_BINDING_OES, (GLint *)&SystemFBO);
// Create the texture and the FBO the will hold the result of applying the first filter
glGenTextures(1, &ResultTexture);
glBindTexture(GL_TEXTURE_2D, ResultTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, wide, high, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glGenFramebuffersOES(1, &ResultFBO);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, ResultFBO);
glFramebufferTexture2DOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_TEXTURE_2D, ResultTexture, 0);
// bind the result FBO
glBindFramebufferOES(GL_FRAMEBUFFER_OES, ResultFBO);
// apply 1st filter
glViewport(0, 0, wide, high);
filter[mode].func(flipquad, val);
// restore original frame buffer object
glBindFramebufferOES(GL_FRAMEBUFFER_OES, SystemFBO);
// use ResultTexture as input for the 2nd filter
glBindTexture(GL_TEXTURE_2D, ResultTexture);
// apply 2nd filter
glViewport(0, 0, wide, high);
filter[2].func(flipquad, val);
glCheckError();
}
最佳答案
您可以通过在两个缓冲区之间交替来扩展此方案:
GLuint stageTextures[2];
glGenTextures(2, stageTextures);
glBindTexture(GL_TEXTURE_2D, stageTexture[0]);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, wide, high, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glBindTexture(GL_TEXTURE_2D, stageTexture[1]);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, wide, high, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
GLuint stageFBO[2];
glGenFramebuffersOES(2, stageFB0);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, stageFBO[0]);
glFramebufferTexture2DOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_TEXTURE_2D, stageTexture[0], 0);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, stageFBO[1]);
glFramebufferTexture2DOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_TEXTURE_2D, stageTexture[1], 0);
// bind stage 1, sourcing stage 0
glBindFramebufferOES(GL_FRAMEBUFFER_OES, stageFBO[1]);
glBindTexture(GL_TEXTURE_2D, stageTexture[0]);
// apply 1st filter
glViewport(0, 0, wide, high);
filter[mode].func(flipquad, val);
glBindTexture(GL_TEXTURE_2D, 0); // must unbind texture before FBO with that texture attached can be bound
// bind stage 0, sourcing stage 1
glBindFramebufferOES(GL_FRAMEBUFFER_OES, stageFBO[0]);
glBindTexture(GL_TEXTURE_2D, stageTexture[1]);
// apply 2nd filter
glViewport(0, 0, wide, high);
filter[mode].func(flipquad, val);
glBindTexture(GL_TEXTURE_2D, 0); // must unbind texture before FBO with that texture attached can be bound
// bind stage 1, sourcing stage 0
glBindFramebufferOES(GL_FRAMEBUFFER_OES, stageFBO[1]);
glBindTexture(GL_TEXTURE_2D, stageTexture[0]);
// apply 3rd filter
glViewport(0, 0, wide, high);
filter[mode].func(flipquad, val);
glBindTexture(GL_TEXTURE_2D, 0); // must unbind texture before FBO with that texture attached can be bound
// and so on. finally
// Bind SystemFBO so the screen is the target, sourcing stage 0/1
// (depending on if a even or odd number of filters involved)
glBindFramebufferOES(GL_FRAMEBUFFER_OES, SystemFBO);
glBindTexture(GL_TEXTURE_2D, stageTexture[...]); // set to follow the scheme above
// apply n-th filter
glViewport(0, 0, wide, high);
filter[mode].func(flipquad, val);