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POopengl shader problems with mrt
 

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  1. POopengl shader problems with mrt
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    <p>I have two textures with same size attached to one fbo, and I want to render another texture into one of the attached textures, and I want to render a blue shape of the figure of the input texture to the other fbo attached texture.</p> <p>the (updated) vertex shader:</p> <pre><code>#version 330 in vec2 coord; out vec2 f_coord; void main() { gl_Position = vec4(coord, 0.0, 1.0); f_coord = (1.0+coord)/2.0; } </code></pre> <p>the (updated) fragment shader:</p> <pre><code>#version 330 uniform sampler2D my_texture; in vec2 f_coord; out vec4 FragData[2]; void main() { if(texture(my_texture,f_coord).a == 0.0) discard; FragData[0]=texture(my_texture,f_coord); FragData[1]=vec4(0.5, 0.5, 1.0, 1.0); } </code></pre> <p>With this fragment shader everything works fine. The texture and the blue stamp of the texture contures are rendered properly.</p> <p>Here is a screenshot: <a href="http://s14.directupload.net/file/d/3487/kvkqdbl7_png.htm" rel="nofollow">http://s14.directupload.net/file/d/3487/kvkqdbl7_png.htm</a></p> <p>But if I want to render the texture into gl_FragData[1] and the blue conture stamp into gl_FragData[0]</p> <pre><code>#version 330 uniform sampler2D my_texture; in vec2 f_coord; out vec4 FragData[2]; void main() { if(texture(my_texture,f_coord).a == 0.0) discard; FragData[0]=vec4(0.5, 0.5, 1.0, 1.0); FragData[1]=texture(my_texture,f_coord); } </code></pre> <p>than I get two totally blue textures. The strange thing is: Both target textures are totally blue, but I have set the glViewport just to a part of the texture.</p> <p>Here a screenshot: <a href="http://s1.directupload.net/file/d/3487/9loqibdc_png.htm" rel="nofollow">http://s1.directupload.net/file/d/3487/9loqibdc_png.htm</a></p> <p>The fbo attachments have the half screen size</p> <pre><code> glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, glutGet(GLUT_WINDOW_WIDTH)/2, glutGet(GLUT_WINDOW_HEIGHT), 0, GL_RGBA, GL_BYTE, 0); </code></pre> <p>So I can render both textures to the screen for checking.</p> <p>This is how I created the framebufferobject</p> <pre><code> void init_fbo() { glGenTextures(1, &amp;fbo.texture0); glBindTexture(GL_TEXTURE_2D, fbo.texture0); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, glutGet(GLUT_WINDOW_WIDTH)/2, glutGet(GLUT_WINDOW_HEIGHT), 0, GL_RGBA, GL_BYTE, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glGenTextures(1, &amp;fbo.texture1); glBindTexture(GL_TEXTURE_2D, fbo.texture1); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, glutGet(GLUT_WINDOW_WIDTH)/2, glutGet(GLUT_WINDOW_HEIGHT), 0, GL_RGBA, GL_BYTE, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glBindTexture(GL_TEXTURE_2D, 0); glGenFramebuffers(1, &amp;fbo.fbo); glBindFramebuffer(GL_FRAMEBUFFER, fbo.fbo); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, fbo.texture0, 0); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, fbo.texture1, 0); glBindFramebuffer(GL_FRAMEBUFFER, 0); } </code></pre> <p>I use those global struct variables</p> <pre><code> struct { GLuint fbo; GLuint texture0; GLuint texture1; } fbo; struct { GLuint program; GLint uni_texture; GLint att_coord; } shader_fbo; struct { GLuint program; GLint uni_texture; GLint att_coord; } shader_screen; </code></pre> <p>And this is my render function</p> <pre><code> void render() { GLenum buffers[2]; GLfloat vertices[] = { -1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0 }; GLubyte indices[] = { 0, 1, 2, 1, 2, 3 }; /*render to mrt fbo*/ glUseProgram(shader_fbo.program); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture.texID); glUniform1i(shader_fbo.uni_texture, 0); glEnableVertexAttribArray(shader_fbo.att_coord); glVertexAttribPointer(shader_fbo.att_coord, 2, GL_FLOAT, GL_FALSE, 0, vertices); glBindFramebuffer(GL_FRAMEBUFFER, fbo.fbo); buffers[0] = GL_COLOR_ATTACHMENT0; buffers[1] = GL_COLOR_ATTACHMENT1; glDrawBuffers(2, buffers); glViewport(0, 0, texture.width, texture.height); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture.texID); glUniform1i(shader_fbo.uni_texture, 0); glClear(GL_COLOR_BUFFER_BIT); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, indices); glDisableVertexAttribArray(shader_fbo.att_coord); glBindFramebuffer(GL_FRAMEBUFFER, 0); glBindTexture(GL_TEXTURE_2D, 0); /*render both textures now to screen*/ glUseProgram(shader_screen.program); glEnableVertexAttribArray(shader_screen.att_coord); glVertexAttribPointer(shader_screen.att_coord, 2, GL_FLOAT, GL_FALSE, 0, vertices); /*render the first texture to the left side of the screen*/ glViewport(0, 0, glutGet(GLUT_WINDOW_WIDTH)/2, glutGet(GLUT_WINDOW_HEIGHT)); glClear(GL_COLOR_BUFFER_BIT); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, fbo.texture0); glUniform1i(shader_screen.uni_texture, 0); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, indices); /*render the second texture to the right side of the screen*/ glViewport(glutGet(GLUT_WINDOW_WIDTH)/2, 0, glutGet(GLUT_WINDOW_WIDTH)/2, glutGet(GLUT_WINDOW_HEIGHT)); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, fbo.texture1); glUniform1i(shader_screen.uni_texture, 0); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, indices); glutSwapBuffers(); } </code></pre>
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    1. PTQuestion
    1. USuser2798943
    1. USuser2798943
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      1. POopengl shader problems with mrt
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      1. VTDownMod
    2. VO
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      1. POopengl shader problems with mrt
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
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      1. POopengl shader problems with mrt
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      1. VTUpMod
    1. COyour shaders are not valid GLSL for version 3.30.
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      1. USderhass
    2. CO@derhass I've deleted the version line from my shader sources. My graphics driver and card support opengl/glsl up to 4.30 - "OpenGL core profile shading language version string: 4.30 NVIDIA via Cg compiler"
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      1. POopengl shader problems with mrt
      1. USuser2798943
    3. COwell, are you using a core profile or compatibility?
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      1. POopengl shader problems with mrt
      1. USderhass
 

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