opengl-es-1.1 | 易学教程

Rendering multiple textures at different points on screen without using point sprites

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问题 I'm building an ios drawing app and am having a hard time how to draw paint textures on the screen at different points. Most tutorials online refer to rendering a single texture of a certain size on screen. However, what I'm looking for is to provide an array of 2d vertices at which to draw the paint texture that is computed based on where the user touches on the screen. I was using point sprites which didn't require me to specify the texture coordinates and hte primitive object used to draw

Rendering multiple textures at different points on screen without using point sprites

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VBO doesn't draw anything

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问题 I am trying to draw a square with VBO in my native blackberry 10 application. My implementation is, glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glEnable(GL_TEXTURE_2D); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glGenBuffers(1,&decompressTileImage->VBOId); glBindBuffer(GL_ARRAY_BUFFER,decompressTileImage->VBOId); glBufferData(GL_ARRAY_BUFFER,sizeof(tileCoordList)+sizeof

How to set blend function on opengl for two overlapping objects

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问题 Hi I needed to draw a round corner rectangle. I followed the procedure of the above image. I first drew the green rectangle. Then I drew the two black rectangles.And then I drew circles on the edges to make the corner round. Now what I get after doing this is in the image below. As it can be seen that the corner circles have less transparency on the portions where they overlap with the rectangles. But more transparency when not overlapped with the rectangles. The rectangles have alpha set to

OpenGL debugging

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问题 When I write OpenGL (1.0) programs for Android, I found it not easy to debug my programs. OpenGL is just a fixed pipeline of several steps which process vertex coordintates. Is there any way to peek and see what are results of consecutive steps of the pipeline? Added: Mad Scientist, thanks for your advice. However, I tried to use Tracer for OpenGL ES (following instructions from http://developer.android.com/tools/help/gltracer.html ) and I'm still not sure on how do I find the information I

OpenGL ES - How to Batch Render 500+ particles w/ different alphas, rotations, and scales?

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问题 I am developing an iOS game that will need to render 500-800 particles at a time. I have learned that it is a good idea to batch render many sprites in OpenGL ES instead of calling glDrawArrays(..) on every sprite in the game in order to be able to render more sprites w/out a drastic reduction in frame rate. My question is : how do I batch render 500+ particles that all have different alphas, rotations, and scales, but share the same texture atlas? The emphasis of this question is on the

Rendering multiple textures at different points on screen without using point sprites

阅读更多关于 Rendering multiple textures at different points on screen without using point sprites

I'm building an ios drawing app and am having a hard time how to draw paint textures on the screen at different points. Most tutorials online refer to rendering a single texture of a certain size on screen. However, what I'm looking for is to provide an array of 2d vertices at which to draw the paint texture that is computed based on where the user touches on the screen. I was using point sprites which didn't require me to specify the texture coordinates and hte primitive object used to draw the texture. However, I'd like to use texture-coordinates to provide a primitive object (like a quad