我遇到了一个无法自行解决的难题,希望有人能够帮助我。
我一直在尝试使用GLSL创建一个漂亮的花开效果,这个效果非常好。当我尝试将一些移动物体包含到场景中时,我注意到我忘记在渲染之前清除我的FBOs。
如果不清除,它可以在从未改变场景的情况下工作,因为我一直在使用相同的纹理。使用glClear()命令仍然可以工作,但是只有在第一帧之后,所有我得到的就是黑屏。所以我想我的问题是我无法使我的FBOs每一帧都得到更新。
我感觉我可能要么是缺少了非常明显的东西,要么是做错了什么。
如果您有任何建议,我将不胜感激。
以下是我在第一帧中得到的内容:
![enter image description here](https://istack.dev59.com/1UECh.webp)
来源: (使用openFrameworks)
设置:
void testApp::setup(){
ofSetVerticalSync(true);
ofDisableSetupScreen();
width = ofGetWidth();
height = ofGetHeight();
//complie/link/generate ShaderObjects ....
horizontalBlurFrag.load("/opt/openframeworks/apps/examples/FBO_basic_shader_new_continued_v4_2/bin/data/fragment_shader_horizontal.glsl", GL_FRAGMENT_SHADER);
verticalBlurFrag.load("/opt/openframeworks/apps/examples/FBO_basic_shader_new_continued_v4_2/bin/data/fragment_shader_vertical.glsl", GL_FRAGMENT_SHADER);
BlurVertex.load("/opt/openframeworks/apps/examples/FBO_basic_shader_new_continued_v4_2/bin/data/horizontal_blur.glsl", GL_VERTEX_SHADER);
blendTextures.load("/opt/openframeworks/apps/examples/FBO_basic_shader_new_continued_v4_2/bin/data/blend_shader.glsl", GL_FRAGMENT_SHADER);
fboOriginal.initialize(width, height);
fboH800.initialize(width, height);
fboV800.initialize(width, height);
fboH400.initialize(width, height);
fboV400.initialize(width, height);}
绘制:
void testApp::draw(){
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
//set orthographic projection
glOrtho( -1, 1, -1, 1, 1.0, 40.0 );
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
glViewport( 0, 0, width, height);
glDisable(GL_TEXTURE_2D);
fboOriginal.bind();
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushAttrib(GL_VIEWPORT_BIT);
glViewport(0, 0, width, height);
glPushMatrix();
glScalef(0.1f, 0.1f, 1.0f);
//generating values between 0 and 2
float x = 2 * (sin(time)+1.000001)/2;
//drawSOlidRect(xPos, yPos, width, height, red, green, blue);
drawSolidRect(-8.0f, 8.0f, x, x, 0.4f, 0.4f, 1.0f);
drawSolidRect(-5.0f, 8.0f, x, x, 0.4f, 1.0f, 0.4f);
drawSolidRect(-2.0f, 8.0f, x, x, 0.4f, 1.0f, 1.0f);
drawSolidRect( 1.0f, 8.0f, x, x, 1.0f, 0.4f, 0.4f);
drawSolidRect( 4.0f, 8.0f, x, x, 1.0f, 0.4f, 1.0f);
drawSolidRect( 7.0f, 8.0f, x, x, 1.0f, 1.0f, 0.4f);
glPopMatrix();
glPopAttrib();
fboOriginal.unbind();
glEnable(GL_TEXTURE_2D);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, fboOriginal.fboTexture);
BlurVertex.enable();
horizontalBlurFrag.enable();
glUniform1i(glGetUniformLocation(horizontalBlurFrag.program, "RTScene"), 0);
glDisable(GL_TEXTURE_2D);
fboH800.bind();
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushAttrib(GL_VIEWPORT_BIT);
glViewport(0, 0, width, height);
glPushMatrix();
glBegin(GL_QUADS);
glColor3f(1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0, 1.0, -1.0);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0, 1.0, -1.0);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0, -1.0, -1.0);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0, -1.0, -1.0);
glEnd();
glPopMatrix();
glPopAttrib();
glDisable(GL_TEXTURE_2D);
fboH800.unbind();
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fboH800.fboTexture);
BlurVertex.enable();
verticalBlurFrag.enable();
glUniform1i(glGetUniformLocation(verticalBlurFrag.program, "RTBlurH"), 0);
glDisable(GL_TEXTURE_2D);
fboV800.bind();
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushAttrib(GL_VIEWPORT_BIT);
glViewport(0, 0, width, height);
glPushMatrix();
glBegin(GL_QUADS);
glColor3f(1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0, 1.0, -1.0);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0, 1.0, -1.0);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0, -1.0, -1.0);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0, -1.0, -1.0);
glEnd();
glPopMatrix();
glPopAttrib();
fboV800.unbind();
glEnable(GL_TEXTURE_2D);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, fboV800.fboTexture);
BlurVertex.enable();
horizontalBlurFrag.enable();
glUniform1i(glGetUniformLocation(horizontalBlurFrag.program, "RTScene"), 1);
glDisable(GL_TEXTURE_2D);
fboH400.bind();
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushAttrib(GL_VIEWPORT_BIT);
glPushMatrix();
glViewport(0, 0, width/4, height/4); //crude downscale
glBegin(GL_QUADS);
glColor3f(1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0, 1.0, -1.0);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0, 1.0, -1.0);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0, -1.0, -1.0);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0, -1.0, -1.0);
glEnd();
glPopMatrix();
glPopAttrib();
glDisable(GL_TEXTURE_2D);
fboH400.unbind();
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fboH400.fboTexture);
BlurVertex.enable();
verticalBlurFrag.enable();
glUniform1i(glGetUniformLocation(verticalBlurFrag.program, "RTBlurH"), 1);
glDisable(GL_TEXTURE_2D);
fboV400.bind();
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushAttrib(GL_VIEWPORT_BIT);
glPushMatrix();
glViewport(0, 0, width*4, height*4); //crude downscale
glBegin(GL_QUADS);
glColor3f(1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1.0, 1.0, -1.0);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1.0, 1.0, -1.0);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1.0, -1.0, -1.0);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1.0, -1.0, -1.0);
glEnd();
glPopMatrix();
glPopAttrib();
glDisable(GL_TEXTURE_2D);
fboV400.unbind();
glBindTexture(GL_TEXTURE_2D, 0);
glEnable(GL_TEXTURE_2D);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, fboV800.fboTexture);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, fboV400.fboTexture);
BlurVertex.enable();
blendTextures.enable();
glUniform1i(glGetUniformLocation(blendTextures.program, "originalSizeTex"), 0);
glUniform1i(glGetUniformLocation(blendTextures.program, "downscaledTex"), 1);
glDisable(GL_TEXTURE_2D);
glBegin(GL_QUADS);
glColor3f(1.0f, 1.0f, 1.0f);
glMultiTexCoord2fARB(GL_TEXTURE0, 0.0f, 1.0f);
glVertex3f(-1.0, 1.0, -1.0);
glMultiTexCoord2fARB(GL_TEXTURE0, 1.0f, 1.0f);
glVertex3f(1.0, 1.0, -1.0);
glMultiTexCoord2fARB(GL_TEXTURE0, 1.0f, 0.0f);
glVertex3f(1.0, -1.0, -1.0);
glMultiTexCoord2fARB(GL_TEXTURE0, 0.0f, 0.0f);
glVertex3f(-1.0, -1.0, -1.0);
glEnd();
glDisable(GL_TEXTURE_2D);}
FBO:
class FrameBufferObject{
public:
//handles
GLuint fbo, fboTexture, fboDepthbuffer;
public:
void initialize(GLuint width, GLuint height){
// generate namespace for the frame buffer, colorbuffer and depthbuffer
glGenFramebuffersEXT(1, &fbo);
glGenTextures(1, &fboTexture);
glGenRenderbuffersEXT(1, &fboDepthbuffer);
//switch to our fbo so we can bind stuff to it
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo);
//create the colorbuffer texture and attach it to the frame buffer
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, fboTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glGenerateMipmapEXT(GL_TEXTURE_2D);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT,GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, fboTexture, 0);
// create a render buffer as our depthbuffer and attach it
glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fboDepthbuffer);
glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT24,width, height);
glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, fboDepthbuffer);
// Go back to regular frame buffer rendering
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
glDisable(GL_TEXTURE_2D);
}
void bind(){
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo);
}
void unbind(){
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
}
void clear(){
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
}};
更新:
glClearColor中的alpha值似乎是我的问题的一部分。
我尝试调整它,得到的结果是这样的: (使用上下缩放的四边形,就像您期望的那样)
不知何故,我似乎在某个地方失去了所有颜色。 奇怪的是,我在我的4个FBO中设置(0, 0, 0, 0),并且为其中一个设置(0, 0, 0, 1),得到了最佳结果。将所有FBO的值设置为(0, 0, 0, 0)只会产生略带灰色的图片(我认为这是没有任何内容的默认窗口)。
这是我的“混合着色器”:
uniform sampler2D originalSizeTex;
uniform sampler2D downscaledTex;
varying vec2 vTexCoord;
void main(void){
vec4 colorOriginal = vec4(0.0, 0.0, 0.0, 0.0);
vec4 colorDownscale = vec4(0.0, 0.0, 0.0, 0.0);
colorOriginal = texture2D(originalSizeTex, vTexCoord.xy);
colorDownscale = texture2D(downscaledTex, vTexCoord.xy);
gl_FragColor = vec4(colorOriginal + colorDownscale);
}
有什么猜测吗?