glDrawArrays() slow on iPad?
- by Nick
Hey guys,
I was wondering how to speed up my iPad application using OpenGLES 2.0. At the moment we have every drawable object draw itself with a call to glDrawArrays(). Blend mode is on, we really need it. Without disabling blendmode, how would we improve performance for this app?
For instances, if we now draw 1 texture across the whole screen, the app only gets 15FPS, which is really slow I think? Are we doing something terribly wrong? Our drawing code (for each drawable), is as follows:
- (void) draw {
GLuint textureAvailable = 0;
if(texture != nil){
textureAvailable = 1;
}
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture.name);
glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, vertices);
glEnableVertexAttribArray(ATTRIB_VERTEX);
glVertexAttribPointer(ATTRIB_COLOR, 4, GL_FLOAT, 1, 0, colorsWithMultipliedAlpha);
glEnableVertexAttribArray(ATTRIB_COLOR);
glVertexAttribPointer(ATTRIB_TEXTUREMAP, 2, GL_FLOAT, 1, 0, textureMapping);
glEnableVertexAttribArray(ATTRIB_TEXTUREMAP);
//Note that we are NOT using position.z here because that is only used to determine drawing order
int *jnUniforms = JNOpenGLConstants::getInstance().uniforms;
glUniform4f(jnUniforms[UNIFORM_TRANSLATE], position.x, position.y, 0.0, 0.0);
glUniform4f(jnUniforms[UNIFORM_SCALE], scale.x, scale.y, 1.0, 1.0);
glUniform1f(jnUniforms[UNIFORM_ROTATION], rotation);
glUniform1i(jnUniforms[UNIFORM_TEXTURE_SAMPLE], 0);
glUniform2f(jnUniforms[UNIFORM_TEXTURE_REPEAT], textureRepeat.x, textureRepeat.y);
glUniform1i(jnUniforms[UNIFORM_TEXTURE_AVAILABLE], textureAvailable);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}
