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use depth buffer to avoid writing to opaque fragments

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This commit is contained in:
Konstantin Käfer
2014-03-04 11:21:42 +01:00
parent dfed81e218
commit e85304d510
3 changed files with 48 additions and 9 deletions
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2
include/llmr/renderer/painter.hpp
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@@ -50,6 +50,7 @@ private:
void useProgram(uint32_t program);
void lineWidth(float lineWidth);
void depthMask(bool value);
public:
mat4 matrix;
@@ -64,6 +65,7 @@ private:
uint32_t gl_program = 0;
float gl_lineWidth = 0;
bool gl_depthMask = true;
std::unique_ptr<PlainShader> plainShader;
std::unique_ptr<OutlineShader> outlineShader;

1
ios/MBXViewController.mm
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@@ -78,6 +78,7 @@ class MBXMapView
view.enableSetNeedsDisplay = NO;
view.drawableStencilFormat = GLKViewDrawableStencilFormat8;
view.drawableDepthFormat = GLKViewDrawableDepthFormat16;
[view bindDrawable];
[EAGLContext setCurrentContext:self.context];

54
src/renderer/painter.cpp
View File

@@ -37,15 +37,21 @@ void Painter::setup() {
assert(linejoinShader);
assert(patternShader);
glEnable(GL_STENCIL_TEST);
// Blending
// We are blending the new pixels *behind* the existing pixels. That way we can
// draw front-to-back and use then stencil buffer to cull opaque pixels early.
glEnable(GL_BLEND);
glBlendFunc(GL_ONE_MINUS_DST_ALPHA, GL_ONE);
// Set clear values
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glClearDepth(1.0f);
glClearStencil(0x0);
// Stencil test
glEnable(GL_STENCIL_TEST);
glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
}
void Painter::setupShaders() {
@@ -71,6 +77,13 @@ void Painter::lineWidth(float lineWidth) {
}
}
void Painter::depthMask(bool value) {
if (gl_depthMask != value) {
glDepthMask(value ? GL_TRUE : GL_FALSE);
gl_depthMask = value;
}
}
void Painter::changeMatrix() {
// Initialize projection matrix
matrix::ortho(projMatrix, 0, transform.width, transform.height, 0, 1, 10);
@@ -89,10 +102,11 @@ void Painter::changeMatrix() {
void Painter::prepareClippingMask() {
useProgram(plainShader->program);
glDisable(GL_DEPTH_TEST);
glColorMask(false, false, false, false);
glStencilMask(0xFF);
glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
// This has been set by the call to Painter::clear()
// glStencilMask(0xFF);
coveringPlainArray.bind(*plainShader, tileStencilBuffer, BUFFER_OFFSET(0));
}
@@ -106,11 +120,15 @@ void Painter::drawClippingMask(const mat4& matrix, uint8_t clip_id) {
void Painter::finishClippingMask() {
glColorMask(true, true, true, true);
glEnable(GL_STENCIL_TEST);
glEnable(GL_DEPTH_TEST);
glStencilMask(0x0);
}
void Painter::clear() {
glClear(GL_COLOR_BUFFER_BIT);
glStencilMask(0xFF);
depthMask(true);
// glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glClear(GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}
void Painter::render(const Tile::Ptr& tile) {
@@ -187,6 +205,7 @@ void Painter::renderFill(FillBucket& bucket, const std::string& layer_name, cons
lineWidth(2.0f); // This is always fixed and does not depend on the pixelRatio!
outlineShader->setColor(stroke_color);
depthMask(false);
// Draw the entire line
outlineShader->setWorld({{ transform.fb_width, transform.fb_height }});
@@ -238,6 +257,11 @@ void Painter::renderFill(FillBucket& bucket, const std::string& layer_name, cons
patternShader->setMix(mix);
style.sprite->bind(true);
// TODO: Find out if the texture is completely opaque. If it is, we can
// set the mask to GL_TRUE so that we won't draw any further fragments
// after this one.
depthMask(false);
// Draw the actual triangles into the color & stencil buffer.
bucket.drawElements(*patternShader);
} else {
@@ -246,6 +270,10 @@ void Painter::renderFill(FillBucket& bucket, const std::string& layer_name, cons
plainShader->setMatrix(matrix);
plainShader->setColor(fill_color);
// Only update the depth buffer if the color we're drawing is completely
// opaque.
depthMask(fill_color[3] >= 1.0f);
// Draw the actual triangles into the color & stencil buffer.
bucket.drawElements(*plainShader);
}
@@ -352,6 +380,7 @@ void Painter::renderLine(LineBucket& bucket, const std::string& layer_name, cons
lineShader->setRatio(tilePixelRatio);
lineShader->setColor(color);
lineShader->setDebug(0);
depthMask(false);
bucket.drawLines(*lineShader);
}
}
@@ -391,10 +420,17 @@ void Painter::renderPoint(PointBucket& bucket, const std::string& layer_name, co
pointShader->setPointTopLeft({{ imagePos.tl.x, imagePos.tl.y }});
pointShader->setPointBottomRight({{ imagePos.br.x, imagePos.br.y }});
style.sprite->bind(transform.rotating || transform.scaling || transform.panning);
depthMask(false);
bucket.drawPoints(*pointShader);
}
void Painter::renderDebug(const Tile::Ptr& tile) {
// Disable depth test and don't count this towards the depth buffer,
// but *don't* disable stencil test, as we want to clip the red tile border
// to the tile viewport.
glDisable(GL_DEPTH_TEST);
depthMask(false);
// Blend to the front, not the back.
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
useProgram(plainShader->program);
@@ -417,10 +453,11 @@ void Painter::renderDebug(const Tile::Ptr& tile) {
// Revert blending mode to blend to the back.
glBlendFunc(GL_ONE_MINUS_DST_ALPHA, GL_ONE);
glEnable(GL_DEPTH_TEST);
}
void Painter::renderMatte() {
glDisable(GL_STENCIL_TEST);
glStencilFunc(GL_EQUAL, 0x0, 0xFF);
Color white = {{ 0.9, 0.9, 0.9, 1 }};
@@ -431,18 +468,17 @@ void Painter::renderMatte() {
matteArray.bind(*plainShader, matteBuffer, BUFFER_OFFSET(0));
plainShader->setColor(white);
glDrawArrays(GL_TRIANGLES, 0, (GLsizei)matteBuffer.index());
glEnable(GL_STENCIL_TEST);
}
void Painter::renderBackground() {
Color white = {{ 1, 1, 1, 1 }};
Color fill_color = {{ 1, 1, 1, 1 }};
useProgram(plainShader->program);
plainShader->setMatrix(matrix);
// Draw the clipping mask
coveringPlainArray.bind(*plainShader, tileStencilBuffer, BUFFER_OFFSET(0));
plainShader->setColor(white);
plainShader->setColor(fill_color);
depthMask(fill_color[3] >= 1.0f);
glDrawArrays(GL_TRIANGLES, 0, (GLsizei)tileStencilBuffer.index());
}