我正在学习opengl es 2.0。我正在尝试在 opengl es 2.0 中应用正射投影我画了一个正方形,但实际上我没有在屏幕上得到正方形。而且我不确定我缺少哪一部分。感谢您的帮助!setupRenderingEnv 中有一些我没有发布的方法。但这些方法用于设置框架并且效果很好。并且 m_program 创建得很好。再次感谢您的帮助。
// my vertex shader
attribute vec4 Position;
attribute vec4 SourceColor;
uniform mat4 Projection;
varying vec4 DestinationColor;
void main(void)
{
DestinationColor = SourceColor;
gl_Position = Projection * Position;
}
// my drawing file
typedef struct
{
float Position[3];
float Color[4];
}Vertex;
const Vertex Vertices[] =
{
{{100, -100, 0}, {1, 0, 0, 1}},
{{100, 100, 0}, {0, 1, 0, 1}},
{{-100, 100, 0}, {0, 0, 1, 1}},
{{-100, -100, 0}, {0, 0, 0, 1}}
};
const GLubyte Indices[] =
{
0, 1, 2,
2, 3, 0
};
- (void)setupRenderingEnv
{
[super setupRenderingEnv];
[self setupVertexBufferObjects];
[self setupRunLoop];
[self applyOrthoWithX:self.frame.size.width andY:self.frame.size.height];
glViewport(0, 0, self.frame.size.width, self.frame.size.height);
}
//-- used for applying ortho in opengl es 2.0
- (void)applyOrthoWithX:(float)maxX andY:(float)maxY
{
float a = 1.0f / maxX;
float b = 1.0f / maxY;
float ortho[16] =
{
a, 0, 0, 0,
0, b, 0, 0,
0, 0, -1, 0,
0, 0, 0, 1
};
GLint projectionUniform = glGetUniformLocation(super.m_programHandle, "Projection");
glUniformMatrix4fv(projectionUniform, 1, 0, &ortho[0]);
}
//-- overriding drawCandle. it render image, draw candle
- (void)drawCandle
{
glClearColor(0, 104.0/255, 55.0/255, 1.0);
glClear(GL_COLOR_BUFFER_BIT);
GLuint positionSlot = glGetAttribLocation(super.m_programHandle, "Position");
GLuint colorSlot = glGetAttribLocation(super.m_programHandle, "SourceColor");
glEnableVertexAttribArray(positionSlot);
glEnableVertexAttribArray(colorSlot);
glVertexAttribPointer(positionSlot, 3, GL_FLOAT, GL_FALSE,
sizeof(Vertex), 0);
glVertexAttribPointer(colorSlot, 4, GL_FLOAT, GL_FALSE,
sizeof(Vertex), (GLvoid *)(sizeof(float) * 3));
glDrawElements(GL_TRIANGLES, sizeof(Indices)/sizeof(Indices[0]), GL_UNSIGNED_BYTE, 0);
glDisableVertexAttribArray(positionSlot);
glDisableVertexAttribArray(colorSlot);
[super drawCandle];
}