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Search found 7 results on 1 pages for 'gldrawpixels'.

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• Equiv of glDrawpixels that operates on GPU memory?

  - by anon

  glDrawPixels(GLsizei width, GLsizei height, GLenum format, GLenum type, const ovid *pixels); Is there a function like this, except instead of accessing CPU memory, it accesses GPU memory? [Either a texture of a frame buffer object]

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• Restoring a saved opengl ES buffer (i.e. writing it back to screen)

  - by Adam

  I'm writing an iPhone app where I need to save and load the screen contents. I was able to save the screen using glReadPixels(), but since there's no glDrawPixels() in openGL ES, I'm having a lot of trouble restoring that buffer to the screen. I gather that I need to save the screen as a texture: http://stackoverflow.com/questions/708760/what-is-the-equivalent-of-gldrawpixels-in-opengl-es-1-1 But I'm not sure how to implement this. Does anyone have or know of any code samples that do this? I'm an openGL noob, so any help would be greatly appreciated :)

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• Is OpenGL 1.x deprecated?

  - by QuasarDonkey

  I'm familiar with OpenGL 1.x. I typically use SDL with OpenGL 1.4 on Linux, and I've never run into problems, even on my modern system. I've read on the OpenGL site about deprecation and compatibility contexts, but I'm still unclear as to whether it's safe to continue to use old versions of OpenGL, as opposed to using old features in newer versions. When functionality is marked deprecated ... future versions of OpenGL may remove it. Does deprecation simply imply that those functions can't be used alongside newer features? More specifically, are there any systems today (other than embedded) where OpenGL 1.x isn't available? The old-skool stuff like, glBegin, glEnd, glDrawPixels, etc. Note: I'm not a professional games developer, so you'll have to excuse my ignorance. I'm working on a mostly 2D game that I would like to keep multi-platform, supporting at least Linux, Mac, and Windows.

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• opengl invert framebuffer pixels

  - by ToxIk

  I was wondering was the best way to invert the color pixels in the frame buffer is. I know it's possible to do with glReadPixels() and glDrawPixels() but the performance hit of those calls is pretty big. Basically, what I'm trying to do is have an inverted color cross-hair which is always visible no matter what's behind it. For instance, I'd have an arbitrary alpha mask bitmap or texture, have it render without depth test after the scene is drawn, and all the frame buffer pixels under the masked (full alpha) pixels of the texture would be inverted. I've been trying to do this with a texture, but I'm getting some strange results, also all the blending options I still find confusing.

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• Visualize the depth buffer

  - by Thanatos

  I'm attempting to visualize the depth buffer for debugging purposes, by drawing it on top of the actual rendering when a key is pressed. It's mostly working, but the resulting image appears to be zoomed in. (It's not just the original image, in an odd grayscale) Why is it not the same size as the color buffer? This is what I'm using the view the depth buffer: void get_gl_size(int &width, int &height) { int iv[4]; glGetIntegerv(GL_VIEWPORT, iv); width = iv[2]; height = iv[3]; } void visualize_depth_buffer() { int width, height; get_gl_size(width, height); float *data = new float[width * height]; glReadPixels(0, 0, width, height, GL_DEPTH_COMPONENT, GL_FLOAT, data); glDrawPixels(width, height, GL_LUMINANCE, GL_FLOAT, data); delete [] data; }

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• How to write to the OpenGL Depth Buffer

  - by Mikepote

  I'm trying to implement an old-school technique where a rendered background image AND preset depth information is used to occlude other objects in the scene. So for instance if you have a picture of a room with some wires hanging from the ceiling in the foreground, these are given a shallow depth value in the depthmap, and when rendered correctly, allows the character to walk "behind" the wires but in front of other objects in the room. So far I've tried creating a depth texture using: glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, Image.GetWidth(), Image.GetHeight(), 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, pixels); Then just binding it to a quad and rendering that over the screen, but it doesnt write the depth values from the texture. I've also tried: glDrawPixels(Image.GetWidth(), Image.GetHeight(), GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, pixels); But this slows down my framerate to about 0.25 fps... I know that you can do this in a pixelshader by setting the gl_fragDepth to a value from the texture, but I wanted to know if I could achieve this with non-pixelshader enabled hardware?

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• Why is my Python OpenGL render2DTexture function so slow?

  - by Barakat

  SOLVED: The problem was actually using time.time() every CPU cycle to see whether the next frame should be drawn or not. The time it takes to execute time.time() was having an impact on the FPS. I made this function for drawing 2D textures as images in a 2D view in my OpenGL application. After doing some testing I found that it takes up 1-2 fps per texture. I know I am probably doing something wrong in this code. Any ideas? I am limiting the FPS to 60. Edit: When I disable the texture rendering it adds about 15% fps back. When I disabled text rendering it adds about 15% fps back. When i disable both barely any fps is consumed anymore. IE: 20 out of 60 fps with both on. 30 out of 60 when one is disabled. 58 out of 60 when both are disabled. When rendering the text on a button ( the control I'm using to test this ), it only "prepares" the text when the button label is set. Updated code, still running at the same speed but still works the same: def render2DTexture( self, texture, rect, texrect ): glEnable( GL_TEXTURE_2D ) glBindTexture( GL_TEXTURE_2D, texture ) glBegin( GL_QUADS ) glTexCoord2f( texrect.left, texrect.bottom ) glVertex2i( rect.left, self.windowSize[1] - rect.top ) glTexCoord2f( texrect.right, texrect.bottom ) glVertex2i( rect.left + rect.right, self.windowSize[1] - rect.top ) glTexCoord2f( texrect.right, texrect.top ) glVertex2i( rect.left + rect.right, self.windowSize[1] - ( rect.top + rect.bottom ) ) glTexCoord2f( texrect.left, texrect.top ) glVertex2i( rect.left, self.windowSize[1] - ( rect.top + rect.bottom ) ) glEnd() glDisable( GL_TEXTURE_2D ) def prepareText( self, text, fontFace, color ): self.loadFont( fontFace ) bmp = self.fonts[ fontFace ].render( text, 1, color ) return ( pygame.image.tostring( bmp, 'RGBA', 1 ), bmp.get_width(), bmp.get_height() ) def renderText( self, pText, position ): glRasterPos2i( position[0], self.windowSize[1] - ( position[1] + pText[2] ) ) glDrawPixels( pText[1], pText[2], GL_RGBA, GL_UNSIGNED_BYTE, pText[0] )

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