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POIs there a way to put in a buffer FBO texture output format GL_ALPHA?
 

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  1. POIs there a way to put in a buffer FBO texture output format GL_ALPHA?
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    <p>I am using ftgl font library.</p> <p>ftgl function to create image has this code:</p> <pre><code>glBindTexture(GL_TEXTURE_2D, textID); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, textureWidth, textureHeight,0, GL_ALPHA, GL_UNSIGNED_BYTE, textureMemory); </code></pre> <p>Format GL_ALPHA.</p> <p>When I render to FBO images(GL_RGBA) they look ok. But when I render fonts to fbo texture, there is some problems with colour and alpha.</p> <p>This image should open in editor that don't touch pixels(browser uses anti-aliasing).</p> <p><img src="https://i.stack.imgur.com/cyqgx.png" alt=""></p> <hr> <p>Code:</p> <p>/// 1 step create FBO</p> <pre><code> // Create the color buffer glGenTextures(1, &amp;id_tex); glBindTexture(GL_TEXTURE_2D, id_tex); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, wid, hei, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); // GL_RGBA GL_ALPHA // Create the frame buffer glGenFramebuffersEXT(1, &amp;id_buf); glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, id_buf); glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, id_tex, 0); GLenum err = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT); assert(err == GL_FRAMEBUFFER_COMPLETE_EXT); glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); </code></pre> <p>/// 2 step render to fbo</p> <pre><code>glBindTexture(GL_TEXTURE_2D, 0); glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, id_buf); glEnable(GL_TEXTURE_2D); glEnable(GL_ALPHA_TEST); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glClearColor (0.0f, 0.0f, 0.0f, 0.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glViewport(0,0, 1920 , 1080); </code></pre> <p>ftgl::render();</p> <pre><code>glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); glDisable(GL_TEXTURE_2D); glFlush (); glDisable(GL_BLEND); glDisable(GL_ALPHA_TEST); glViewport (0, 0, 1920, 1080); glClearColor (0.0f, 0.0f, 0.0f, 1.0f); </code></pre> <p>/// 3 step render texture</p> <pre><code>glEnable(GL_TEXTURE_2D); glEnable(GL_ALPHA_TEST); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_COLOR); glBindTexture(GL_TEXTURE_2D, id_tex); glBegin(GL_QUADS); glTexCoord2d(0,0); glVertex3f(point4.X , point4.Y , point4.Z); glTexCoord2d(0,1); glVertex3f(point1.X , point1.Y , point1.Z); glTexCoord2d(1,1); glVertex3f(point2.X , point2.Y , point2.Z); glTexCoord2d(1,0); glVertex3f(point3.X , point3.Y , point3.Z); glEnd(); glDisable(GL_BLEND); glDisable(GL_ALPHA_TEST); glDisable(GL_TEXTURE_2D); </code></pre>
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    1. PTQuestion
    1. USmanking
    1. USmanking
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    1. VO
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      1. POIs there a way to put in a buffer FBO texture output format GL_ALPHA?
      1. This table or related slice is empty.
      1. VTApproveEditSuggestion
    1. COI don't understand what the problem is. You say that "there is some problems with colour and alpha". OK: what are the problems?
      singulars
      1. POIs there a way to put in a buffer FBO texture output format GL_ALPHA?
      1. USNicol Bolas
    2. COI am not sure if GL_ALPHA is an accepted internal format at all.
      singulars
      1. POIs there a way to put in a buffer FBO texture output format GL_ALPHA?
      1. USBartek Banachewicz
    3. COPixels with transparent deleted or different when i rendering texture from fbo. In image it can be seen.
      singulars
      1. POIs there a way to put in a buffer FBO texture output format GL_ALPHA?
      1. USmanking
 

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